Wastegate Solenoid grounded?

[DennisG01]

I put a different turbo on my truck (non-wastegated). The solenoid is obviously not needed. Eventually, I will take the vac pump off, but for the time being I plugged the rubber sleeve (that normally attaches to the wastegate vac canister).

I've been, sporadically, getting the P0236 code. I believe the plug I installed is good, but I just noticed that the small metal bracket (surrounds the solenoid) was broken. I jury rigged it, for now. Code light hasn't gone away (it went away on it's own two days ago, before I even saw the cracked bracket - then it came back this morning).

Is the solenoid grounded through it's bracket? Maybe I didn't "jury" rig it well enough to make a good contact?

What would happen if I unplug the solenoid?

[JohnC]

No, the solenoid does (should) not ground through the bracket. Ground is provided by the PCM. It might complain if the solenoid were removed completely. P0236, however, is more likely caused by the unregulated turbo boost being outside the desired range. You'll have to get a scanner to see what's going on, or at least a boost gauge.

[DennisG01]

I have a boost gauge, and the turbo is making boost - but since it's a non-wastegated turbo, the vac line that goes from the solenoid to the (normally) actual wastegate doesn't do anything - I just plugged it (the rubber sleeve that normally attaches to the wastegate).

I plugged the vac line because, years ago, I had a Turbo Master and Heath sent a small ball bearing that was to be inserted into the rubber sleeve to plug it.

Maybe the solenoid is simply on it's last legs? This one is about 6 years old.

I haven't noticed a problem, but will the P0236 eventually cause a de-fuel?

[DmaxMaverick]

P0236 will cause a defuel. So, if you are defueling, that's a cause. The PCM monitors WG solenoid feedback. If the solenoid is bad, the PCM will complain. It doesn't care what the vacuum line to the actuator is actually connected to, only the result. If you are seeing an overboost code, you are overboosting. You can reduce fuel to reduce the boost, modify the harness to "lie" to the PCM (reduce the perceived boost), or use aftermarket programming (chip) that addresses the issue. The benefit of using aftermarket programming is, you can "ignore" the WG solenoid, as well as increase boost fault triggers. Depending on your turbo performance, it may also increase its efficiency. It's best to contact a custom programmer and discuss what you have and the result you desire.

[DennisG01]

Thanks, guys.

I currently have Kennedy programming (but it is designed with the factory boost control in mind).

EDIT: The Kennedy programming doesn't care how high the boost goes.

OK, de-fueling is going to drastically screw me up right now. We're leaving for vacation on Tuesday. What, if anything, can I do to keep from de-fueling (in the time frame I have)?

Can I leave the vac line open, instead of plugging it? Will that also cause a de-fuel? I don't care, for now, about having the Check Engine light show up - I just can't have the de-fueling (will be towing our boat - about 5 ton).

[DmaxMaverick]

Leaving the vacuum line open or not won't change anything. The PCM doesn't care what's happening at that end. You need to contact Kennedy. He'll have the quickest answer for you.

[DennisG01]

Thanks - I will contact John.

A thought that occurred to me whe I was driving home from work.... What if mounted the wastegate somewhere in the engine bay and reattached the vac line? Could that work, or I am not thinking that through far enough?

[JohnC]

The most likely cause is that the PCM doesn't see the boost level it wants. If the issue occurred immediately after installing the unwastegated turbo, then it's 99.44% sure that's what is happening. As long as the electrical load of the solenoid is correct the PCM doesn't give a hoot about anything else. It is possible that the turbo isn't making enough boost under light loads, but that should not cause a de-fuel. OTOH, if the programming doesn't care how high it goes, that shouldn't either.

What is it doing that causes you to think it is defueling? Do you have a scanner program? If so, what is the wastegate duty cycle doing?

[DmaxMaverick]

Thanks - I will contact John.

A thought that occurred to me whe I was driving home from work.... What if mounted the wastegate somewhere in the engine bay and reattached the vac line? Could that work, or I am not thinking that through far enough?

You're talking to the wrong end of the horse. The PCM (the thing doing all the complaining) doesn't know what is a wastegate. It only modulates the ground circuit to the WG solenoid, and monitors the feedback. 100% electrical. 0% mechanical/pneumatic. If you are having an issue with the boost pressure, according to PCM complaints, it is the result, not the cause it is seeing. You could put a bologna sandwich at the end of that vacuum line, and the PCM will still see and report the same result.

[DmaxMaverick]

In the end, you'll probably find you have the wrong turbo installed for your fuel map, or vise-versa.

[DennisG01]

John - I'm not sure it actually is defueling. But, I haven't done anything else other than city driving. I'm just concerned it WILL once I get a load on it and increase the EGT's.

I don't have a scanner.

It didn't code immediately - maybe after about 45 minutes of driving (split up over a few trips). The idiot light also went out for about a day (50 miles, give or take) before returning.

Dmax - thanks - it saved me from some experimentation.

Since Heath sent a plug along with his Turbo Master, I'm thinking more and more that the problem may just be a faulty solenoid. I sent an email to John - hopefully I'll hear back from him. All I want (hope!) for now, is that we'll be OK for our trip.

[handcannon]

A boost fooler might be what you need for a short term fix. My PO put on a turbomaster and I'd occasionally get an SES light if I pushed too hard getting up to speed. I made a boost fooler and that took care of the occasional SES light.

I don't have the part numbers just off the top of my head, but I think it was a 10K pot that I got from Radio Shack. You should be able to find a wire diagram here for the boost fooler. It was a cheap and easy mod.

Don

[JohnC]

John - I'm not sure it actually is defueling. But, I haven't done anything else other than city driving. I'm just concerned it WILL once I get a load on it and increase the EGT's.


Well you can stop worrying about that. Defueling is a defensive tactic to limit EGT. The reason it is associated with higher EGT's is that it normally occurs in conjunction with a waste gate failure. Since you have no wastegate to fail, defueling in your case would reduce the fuel rate with no change in boost and no increase in EGT.

Defueling can also occur when intake air temps climb, but, again, defueling will lower the temps, not raise them.

Once again, the solenoid has nothing to do with it. The PCM monitors boost and adjusts the solenoid duty cycle to control boost. In your case, no amount of adjusting the duty cycle will have any effect on boost levels, so the PCM declares the solenoid faulty. Little does the PCM know you have removed the wastegate it is so desperate to control.

One thing that could happen, though, is the turbo not making enough boost for the fuel rate. If that happens, your EGTs will go up and you must defuel by lightening up on the pedal.

[suburbanK-2500HD]

Well you can stop worrying about that. Defueling is a defensive tactic to limit EGT. The reason it is associated with higher EGT's is that it normally occurs in conjunction with a waste gate failure. Since you have no wastegate to fail, defueling in your case would reduce the fuel rate with no change in boost and no increase in EGT.

Defueling can also occur when intake air temps climb, but, again, defueling will lower the temps, not raise them.

Once again, the solenoid has nothing to do with it. The PCM monitors boost and adjusts the solenoid duty cycle to control boost. In your case, no amount of adjusting the duty cycle will have any effect on boost levels, so the PCM declares the solenoid faulty. Little does the PCM know you have removed the wastegate it is so desperate to control.

One thing that could happen, though, is the turbo not making enough boost for the fuel rate. If that happens, your EGTs will go up and you must defuel by lightening up on the pedal.

Is there anything other that will cause a defueling exept EGT, i Got SES light and code 078 when towing 2100kg, Turbo pressure was about 0,6-0,7 after the intercooler when it occured, IAT ca. 35-40 degrees, engine temp ca.90 degrees. No reading on the EGT.( tempsensor is after the turbo at the downpipe)

[JohnC]

Is there anything other that will cause a defueling exept EGT,

EGT will not cause de-fueling. the PCM has no way of measuring EGT. The two conditions that I know of that cause de-fueling are:
1) inability to control boost within the programmed parameters. (DTC 78 is the related code.)
2) Intake air temperature higher than expected.

In both cases, de-fueling is a protective measure to limit EGT.

If I read your post correctly, you are showing 0.7 atmospheres of boost, which is around 10 PSI. This is outside the standard programming and will eventually result in DTC 78, de-fueling, and a wastegate duty cycle of 0%. Since you have an after market boost control, the Turbo Master, then it is set too high for your programming. De-fueling in that case will result in lower boost, but still enough to keep EGT's under control. (Removing fuel removes motive force for the turbo, but the mechanical wastegate control doesn't give up.)

[DennisG01]

John, forgive me, but I'm not fully understanding if I'll be OK towing (with full power) with the P0236.

I understand that I'm in control of the EGT's - that's fine, I'm used to that.

But, based on your response To SuburbanK2500, can the code cause a de-fuel, since the PCM thinks things aren't working right?

[JohnC]

can the code cause a de-fuel, since the PCM thinks things aren't working right?

Yes, but, because you do not have a vacuum operated wastegate, the de-fuel will not be accompanied by a loss of boost, so, same air, less fuel = lower EGTs, not higher.

[DmaxMaverick]

I disagree. A wastegate turbo may be able to hold the same boost pressure with less fuel, only because it was against the gate to begin with (dumping some exhaust gas to maintain a specific boost pressure). A non-wastegate turbo, on the other hand, doesn't have that option. Less fuel will be less boost. It is the exhaust gas that drives the turbine, so less exhaust gas is less drive, is less boost.

If your PCM defuels, you WILL have less boost potential. However, you haven't actually seen any indication of a defuel, other than a DTC, which may or may not be causing a defuel. If you have the Kennedy PCM, you should not be seeing this, unless something is significantly out of balance, like a turbo operating well outside its capabilities, or it is failing.

[DennisG01]

OK, got it. So, one way or the other, I need to get this taken care of before our vacation. Hopefully I'll be in touch with John today - I'll post back after I talk with him.

[JohnC]

NO!

I was misunderstood (and my comment could have been better worded.)http://www.cooperjr.skyportservices.net/banghead.gif

My comment should have said "the de-fuel will not be accompanied by a total loss of boost".

When the PCM defuels it also drops the wastegate duty cycle to 0%. In a turbo with a PCM controlled wastegate, there is a near complete loss of boost. The default fuel rate coupled with no boost results in increased (but limited) EGT. Think of it as switching to normally aspirated mode. In your case, the turbo is unaffected by the wastegate duty cycle and will loose (some) boost only due to the lower fuel rate. Most likely this will result in reduced EGTs, not increased. You have an EGT gauge. There should be no problem (other than a lose of power.)

[DennisG01]

Thanks for the clarification, John. Ultimately, loss of power is my main concern. With the 18:1, I've found I can pretty much forget about worrying about high EGT.

I just got off the phone with John. He thinks it's coding because of LOW boost. That makes sense because I'm seeing lower boost numbers (with this turbo) on my gauge than the GM8, in relation to how far I press the throttle pedal. He suggested I get an inexpensive code reader and clear the code, as I'm driving, if it pops up.

I'm gonna take the boat out for a quick tow - see what happens.

[JohnC]

That is possible. As I stated before, that could be an issue as low boost causes elevated EGTs. Again, though, defueling is a defensive measure to limit EGT and, in your case, should result in lower EGTs.

I'm not sure how the '99 programming handles the DTC, but my '95 would clear itself as soon as the condition went away. Simply letting off the pedal and getting back into it would do the trick.

So, why do you have this turbo installed? ;)

[JohnC]

I'm gonna take the boat out for a quick tow - see what happens.

Try Frederick St in Fountain Hill to Wyandotte St. 14% grade...

[DennisG01]

That is possible. As I stated before, that could be an issue as low boost causes elevated EGTs. Again, though, defueling is a defensive measure to limit EGT and, in your case, should result in lower EGTs.

I'm not sure how the '99 programming handles the DTC, but my '95 would clear itself as soon as the condition went away. Simply letting off the pedal and getting back into it would do the trick.

So, why do you have this turbo installed? ;)

Towing up a local hill showed me that I'm not getting full fuel. It seemed as though I was only getting about 75% (just a guess).

Did I catch a little sarcasm in that "why'd I buy it" comment? :)

[DennisG01]

Try Frederick St in Fountain Hill to Wyandotte St. 14% grade...

Ha! I've jogged up that hill, before! I used to teach at the elementary school. Not quite sure I could maneuver 55' of truck and trailer thru there!!!

[JohnC]

I see they made it one way. Where's the fun in that? I remember once years ago I made my mom drive down it so I could see what it was like. She wasn't wild about the idea, but was a good sport... Let's see, I wonder if that was the 55 Ford or the 59 Pontiac Star Chief? :confused:

Not really sarcasm, but I am curious, how you chose that one, and why.

50', huh? The turn at the top might be a bear... Better do it at night! :D

[JohnC]

Towing up a local hill showed me that I'm not getting full fuel. It seemed as though I was only getting about 75% (just a guess).

Was it smoking black? Was the SES light on? If not, it shouldn't defuel... What was the boost?

Check the air and fuel filters! ;)

[DennisG01]

How were the brakes on those cars? :eek:

No smoke (just a haze), about 10PSI, light was still on (P0236). Filters should be good, but I'll clean the air and check the fuel, just in case.

I overnighted a ScangaugeII so I'll have that to play with. I'm hoping that once I've got the boat in tow (since the PSI's will be higher) I'll be OK and the light won't come on. Or maybe it'll just be once in a while and I can clear it while I'm driving... again, mucho hoping.

I don't know exactly how much the ECM was limiting fuel (I guess "limiting" fuel is a better way to describe it than "de-fueling"), but whatever it was, it made the truck feel like it did with the GM-8.

[JohnC]

How were the brakes on those cars? :eek:


Adequate, I guess. I really don't remember much, other than that we did it and it looked like we were driving off the edge of the world. 'Course, I was sittin' a lot lower back then...

Has the light been on the whole time? If so, maybe you have an electrical issue rather than a boost issue. I'm not sure how the newer trucks handle it, but on the '95 the light went out as soon as you backed off the throttle and didn't come back on until the condition occurred again, for 25 seconds, IIRC.

[ronniejoe]

The "A-Team" turbo that you chose is cheaper, but not a good match for the 6.5, as you are finding out.

[DennisG01]

John - other than a few days ago when the light went out by itself for about 50 miles, it's been on constant. Tomorrow I'll unplug and clean the MAP sensor and wastegate solenoid connections, just to be sure.

HEY!!! Your question just made me think of something! During the install of the turbo, I had removed the upper air intake to cut it a little shorter. I reused the gasket (although it didn't come off perfectly), but coated it with copper RTV. Could that be problem? I made sure to put RTV on the two bolts where the bolt holes go all the way through.

Ron, at this point, it just came down to cost. It's not that I think your pricing is unfair or inflated - I don't think that at all. Believe me, I struggled with the decision. But, we'll see how it works out once I get this code thing figured out. I can always sell this turbo down the road and get a different one.

I will say this about the turbo, though... At light to medium throttle, the truck does get up to speed quicker (pulling away from a stop sign for example), even though the boost is only registering between 1 and 2 psi.

[DmaxMaverick]

John - other than a few days ago when the light went out by itself for about 50 miles, it's been on constant. Tomorrow I'll unplug and clean the MAP sensor and wastegate solenoid connections, just to be sure.

HEY!!! Your question just made me think of something! During the install of the turbo, I had removed the upper air intake to cut it a little shorter. I reused the gasket (although it didn't come off perfectly), but coated it with copper RTV. Could that be problem? I made sure to put RTV on the two bolts where the bolt holes go all the way through.

Ron, at this point, it just came down to cost. It's not that I think your pricing is unfair or inflated - I don't think that at all. Believe me, I struggled with the decision. But, we'll see how it works out once I get this code thing figured out. I can always sell this turbo down the road and get a different one.

I will say this about the turbo, though... At light to medium throttle, the truck does get up to speed quicker (pulling away from a stop sign for example), even though the boost is only registering between 1 and 2 psi.


Your experience, with a non-wastegate turbo, should be just the opposite. This tells me the turbine is too small. A lot of boost at the bottom is too little at the top (excessive exhaust back pressure), and an unhappy PCM. It sounds like it's falling flat at mid to higher load. You may be seeing 10 PSI, but that doesn't offset the back pressure required to make it. It is operating outside its efficiency envelope. You are getting all the turbo you paid for.

[ronniejoe]

It's not too small, it's too big. The reduction in back pressure from too large a turbine will allow the engine to feel a little more free at first, but the lack of drive pressure to produce boost will ultimately be disappointing. The first iteration of my turbo had a much larger turbine housing. It made an improvement over the GM4 because of reduction in back pressure, but it was smoky and lazy and wouldn't produce over about 19 - 20 psi boost pressure. With the smaller housing that I am running now, the bottom end response is significantly better than either it's original configuration or that of the GM4. It will also drive to 25+ psi at the top end now. Smoke is reduced and performance is better. EGT is lower, too.

I'll bet when you get a load behind it, it will smoke pretty heavily.

Dennis, that's still a T4 flange isn't it?

[DennisG01]

The code reader/clearer worked liked a charm. Starting in PA, we are just into Maine, now. With the exception of 2 times, the code has pretty much stayed away. I had to clear it twice while on the road.

Except... We started out last evening and made it about 80 miles and then heard this awful screeching sound (coming from about the turbo area) and all of a sudden couldn't make more than 5psi and the black smoke to boot. Fearing the compressor wheel was coming apart, we pulled over and I checked things out. Well, everything looked good and the blades were good and the shaft was good. So, just to be safe, we turned around and limped home. Got in about 11:30pm and started taking things apart... Got lucky... It was just an IC hose that had slipped off - couldn't see it on the side of the road. Headed back out this morning and all has been well.

Ron - you just about hit the nail on the head with the performance (low to midrange is improved). It is better than the GM8, but when I really get hard on the throttle, the EGT's get too high - didn't have that problem before. Although, there is very, very minimal smoke. I can build about 11psi's. For relatively flat towing it does a good job - better than the GM8, but by no means is it "night and day" better. I've got hills around me....

Edit: to clarify about the smoke... If I roll, very smoothly, into the throttle the smoke stays away. If I get into it to quickly, it does take a bit for the turbo to catch up.

[DennisG01]

Ron- what's the difference between a T3 and T4? The mounting flange is bigger but I believe the holes are the same size. I'm not 100% sure though.

[DmaxMaverick]

The code reader/clearer worked liked a charm. Starting in PA, we are just into Maine, now. With the exception of 2 times, the code has pretty much stayed away. I had to clear it twice while on the road.

Except... We started out last evening and made it about 80 miles and then heard this awful screeching sound (coming from about the turbo area) and all of a sudden couldn't make more than 5psi and the black smoke to boot. Fearing the compressor wheel was coming apart, we pulled over and I Becker things out. Well, everything looked good and the blades were good and the shaft was good. So, just be safe, we turned around and limped home. Got in about 11:30pm and started taking things apart... Got lucky... It was just an IC hose that had slipped off - couldn't see it on the side of the road. Beaded back out this morning and all has been well.

Ron - you just about hit the nail on the head with the performance (low to midrange is improved). It is better than the GM8, but when I really get hard on the throttle, the EGT's get too high - didn't have that problem before. Although, there is very, very minimal smoke. I can build about 11psi's. For relatively flat towing it does a good job - better than the GM8, but by no means is it "night and day" better. I've got hills around me....

No. Turbine too small (NOT to confuse "turbine" with the turbo in general). If it were too large, you would have the opposite result: No bottom end, and (the potential for) gobs of boost at the top. Your climbing EGT's at higher RPM's are the result of the too-small turbine, as well. You may have a mis-match of the turbine and compressor, but at the very least, your turbine is too small for the gas you are pushing through it (or trying to).

This is why OEM mfg's choose the wastegate turbo over the non (with the exception of the 1995 Ford 7.3 IDI...how'd that work out?). This gives the ability to produce good performance at lower RPM's, and control boost limits and EGT's at higher loads/RPM's. The only way around this is with two turbos (not actually "twins"): One smaller for low load, and a larger for greater loads. Too many parts to break, IMO.

[ronniejoe]

Again, not to be argumentative, but his turbine is too big. It's way too big. I've had experience with both too small a turbine and too big a turbine. In fact, I've run about six different configurations on my 6.5, so I've been around the block a few times.

His problem is that he doesn't have enough drive pressure to produce adequate boost for the fuel that he has available. At low to mid-range, the reduction in back pressure (drive pressure) does allow the engine to breath better (even at low boost pressures) as compared to the GM8 running higher boost pressure. You can look at the compressor maps and see what I'm talking about.

At the top end, he only has enough drive pressure to build about 11 psi of boost. That isn't moving enough air for the fuel that he has and will cause egt to rise -- believe me, I've been through it.

With a smaller turbine housing, he could get more drive pressure and move more air, bringing egt down.

Now, without giving away everything I've learned through development of my turbo configuration, with a large turbine and waste gated housing (using the same compressor) I was limited to around 19 psi boost at the top end and could only muster 12 - 15 psi in the mid range -- and I never actuated the waste gate. The truck ran much better than it did with the GM4.

Now, to be fair, I had my GM4 wrung out making about 19 psi in the mid range. At the later stages of its use, I had the vacuum pump going straight to the waste gate completely bypassing the solenoid. The turbine housing would choke at high rpm and the boost pressure would fall off (it actually followed a constant rotor speed line on the compressor map -- I did a bunch of analysis and plotting). The maximum that the GM4 could make at 3600 rpm was about 10 psi. It simply couldn't flow enough air to feed the engine at that speed. This caused a significant rise in egt.

The too-big turbine housing improved performance over the GM4, but was not ideal. My truck smoked heavily when pulling hard with it.

Three iterations later, I've found the near perfect match for the 6.5. The housing in my current configuration is about 25% smaller than the original. This has increased drive pressure so that now the waste gate is actually in use. Bottom end response is much better, rivaling the response of the GM4 and I can make 22+ psi through the mid range in a hard pull swelling to 25 psi at 3600 rpm. This turbocharger really flows! Performance truly is night and day from before. In fact I rarely see over 1100 F egt (pre-turbine) even on a high 90's day with the A/C on and pulling hard. Gut running it like this produces a very light gray haze of smoke which is actually less than what I got with the GM4.

If you had ever seen any pictures of the turbocharger that he is using, you would know just by looking at it that the turbine housing is way too big.

The T4 flange was drilled to accept the bolt pattern of the T3 flange on your exhaust manifold. The passages in the turbine housing flange have some overlap with the passage in your manifold, so there is a step in the flow stream. The T4 flange is bigger with larger inlet passages for higher flow machines.

[DennisG01]

Yes, you're right - the flange is re-drilled to match up with the manifold.

[suburbanK-2500HD]

A little question regarding defueling.

Is it correct that the ECM defuels at 235´F / 112.78´C

Ore if the Turbo pressure is to high for the OEM program.

If this is correct, ist it possible to install a 10k pot at the boost sensor to fool the ECM.

Or is this of no use.

Børge

[JohnC]

Is it correct that the ECM defuels at 235´F / 112.78´C

I'm not sure. Are you referring to IAT or coolant?



ist it possible to install a 10k pot at the boost sensor to fool the ECM.

Yes. However, the boost sensor is not a resistive device. You need to install the pot as a voltage divider.

[suburbanK-2500HD]

hi

I referring to IAT

[JohnC]

I checked the '95 diagnostics (don't have '94 but it should be the same). there is no evidence the PCM limits fuel for either high IAT or high coolant temp. there is some sort of performance control in the case where the coolant temp is low and the IAT is high but only as long as ECT is less than 38C (100F)

[suburbanK-2500HD]

Hi

I read tath if IAT is over 205.F in combination with low ECT(below 100F)
It will defuel.

Børge