Searching for the 'X' device...

[Cowracer]

On my 94, it has two operation modes. #1 is "runs like a striped-assed ape" and #2 is "couldn't drive over a housecat without a good run-up"

There is some device or gremlin in this truck that causes it to shift from mode 1 to mode 2.

My truck has a TurboMaster and Heath chip, otherwise bone stock with 160k Miles. It has new filters for fuel, oil and air. It throws no codes at all.

Here is what I know:

Boost:
Mode 1-2# at idle, 7# at 65mph (level) and max at 13#.
Mode 2- 0# till about 2500 rpm 3# at 65mph max out about 9#

Engine temp:
Mode 1-never heats up no matter how hard I whip it (empty at least)
Mode 2- runs up to 210, then the fan kicks in to cool it off going up hills.

Throttle response/acceleration
mode 1-GREAT!
mode 2-Feels like I left the parking brake on

Exhaust smoke:
Mode 1-Light black
Mode 2-puking heavy black untill the boost comes up, Then it lightens up some, but still heavier than mode 1

Now the only factor that SEEMS to control the switch from mode 1 to mode 2 is maybe ambient temps. Generally, if the air temp seems to be over 85 or so, it goes to mode 2. But! (and its a big 'but') NOT ALWAYS. There have been hot days where the truck has run good and cool nights where it did not.

Twice I have actually felt the shift from mode 1 to mode 2 twice while driving, and I have felt the shift the other way once.

Here is what I think could cause it to go into mode 2, and my thoughts on why or why not, and my questions

Turbo/Wastegate
Why? - Lower boost, longer spool ups, black smoke
Why not? - Turbomaster is mechanical, should not vary boost levels from day to day

Question: Could something mechanical in the wastegate be loose and casing it to hang up open, independent of where the shaft is?

Injection pump/FSD
Why? - The FSD is notorious for heat sensitivity
Why Not? - Thick black smoke indicates too much fuel.

Question: Could a thermal fault in the FSD or IP cause an over fuel condition? Would this affect boost pressure?

Injectors
Why? - Original injectors are probably junk, a dead cylinder would certainly cause lower boost and power.
Why not? - They are mechanical devices, heat should not affect them.

Question: could a dribbling fuel injector cause black smoke.

Plugged Cat
Why?

[More Power]

The computer also monitors fuel temperature, intake air temperature, and engine temperature. The fueling rate is determined in-part by the above factors.

Unless you're running an intercooler, I would not adjust the Turbo-Master for more than a sustained 10 psi. More than that will raise the intake air temperature to 300 degrees or more.

If you have an intercooler, a sustained 12 psi would be a good place to begin. The factory GM turbos become increasingly inefficient above 12 psi, and become serious bottlenecks for exhaust flow above 14 psi.

MP

[BuffaloGuy]

Hey Cowracer.
I'd bet my money on a sticking wastegate.

Test it:
If it's in the **** mode and you let off the throttle and hit it again will it occasionally go to striped ass ape mode? If yes, it could just be the wastegate sticking. They are just a rather crude cast flapper valve.

Just curious, how did you get the handle cowracer?
Ken

[patrick m.]

the cat can be "plugged" sometimes and not "plugged" other times. hard to believe?
if the material in the cat has broken up into large chunks, the chunks can move around and sometimes block some of the flow. then with the ever changing conditions with in the exhaust system, the obstruction may move again and this time settle into a position that does not obstruct the air flow as much.

think of the material as a series of tunnels, turn the tunnels sideways.......no flow.

cat gets my vote as the best place to start

[Kennedy]

A stock 6.5 is fairly restricted with the stock exhaust. A chipped/boosted one is worse yet...

[Cowracer]

Thanks Guys, some good stuff there...

More Power, On bad days I have a hell of a time even getting to 10 lbs boost. On the good days, it takes 12-13 lbs with not adverse affects by the seat of my pants. While this definatly is an issue to be addressed later, I dont think that it is the root cause of my current problems.

Now, temp sensors. I CAN belive that one of those little do-dads could be to blame. I have the IAT sensor out of the manifold and secured in a rubber hose for testin purposes, that had no affect. Does the engine temp sensor also drive the temp gauge, or are there two sensors? The temp gauge acts normally in both modes. What about the fuel temp sensor, where is that located, and is it feild replaceable? What about the Baro sensor on the firewall? Could that play into the equation?

As far as the cat/exhaust issue, the new JK exhaust will be put on this weekend. That will answer that question. Is there any way to inspect the wastgate flapper without removing/disasembling the turbo?

No votes for the injectors? Hmmm....

Thanks again,

Tim

[ 08-20-2003, 06:59 AM: Message edited by: Cowracer ]

[Cowracer]

Originally posted by The Buffalo Guy:

Just curious, how did you get the handle cowracer?
Ken, I raced a dirt track stock car for a few years. My wife collects cow figurines and as a joke I put some vinyl black spots on the (white) car before I had it lettered.

After she seen it, I planned on taking them off, but we got to looking at it and it was just different enough to be cool. My old website is still up. You can see pictures at www.cowracer.freeservers.com (http://www.cowracer.freeservers.com)

Tim

[MikeC]

Cowracer,

The advice about limiting your non-intercooled boost is to try and keep your engine running strong and trying to avoid it turning into a pile of useless parts. Hot intake air has some adverse effects on the engine. Pre intercooler install I limited my boost to about 8# and now that it is there I only go to 12#.

This was one piece of advice that was the same from several sources so it seems to be good advice.

Mike

[oldmansax]

Cowracer, I have the same problem (see "Loss of power in hot ambient temperatures" posted on 07/28) but you described it better. Mine normally shows up when it's hot though. I wired the wastegate up for one trip & that seemed to solve the problem but it wasn't real hot & I didn't want to leave it like that for fear of melting the engine. I will be interested to see what the exhaust replacement does for you.

[Dimsdale]

I am leaning to a bad sensor/wiring solution.

I don't know what other scan-type tools might do this, but my Autotap software can record/monitor the electrical output of many, if not all, of the sensors. You can get either/both the actual voltage and the interpreted (i.e. temperature) values that the computer sees. This would be a good way to determine if any of the sensors are screwy.

P.S. Have someone else watch the laptop. Those "unintended lane changes" can be pure hell! ;)

[markelectric]

Sounds similar to a problem I used to have. At one point it went into the crap mode and never returned. I found my wastegate swinging on the shaft. A hit with the TIG welder cured that problem for good. You must pull the turbo to do it. Not as bad as it seems.

[oldmansax]

Just to add to the continuing saga.....I cut the stock exhaust off & replaced it with Kennedy

[ucdavis]

I only know of 3 variables in producing power in a diesel- fuel rate, air volume (boost), and injection timing.
B4 going thru anything else, I'd take a good hour or so & visually check evry sensor connection & wire for abrasion/loose/etc. incl. 15-pin connector behind FFilter & grounds. Intermittents are notorious for this kind of damage. W/a good thorough search, you can more confidently proceed to targeted component examinations and not worry you overlooked wiring probs.
I'd continue by eliminating fuel rate for now; black smoke seems to indicate the thing is dumping at least enough fuel into cylinders.
Injection timing is controlled by direction from PCM to the stepper motor on Rt. side of IP. These things are pretty reliable according to Stanadyne rebuilder locally, but do go bad. I can't recall if this gizmo is hooked into the FSD or its wiring is separate (can rule out bad FSD if separate). Stepper motor actually rotates the internals of the IP by the desired degrees of advance vs. its shaft drive off the front gear. It is an easy swap out for a know good stepper motor (about $85 for new motor or a used one from a dead IP).
If that isn't it I'd concentrate on boost delivery w/the sensor tests & Tmaster mech. checks.

[charliepeterson]

The ECM should set a code if any of the sensors connected to the Injection Pump go out of range. The one thing which will give you trouble and never turn on the SES is the PMD. Make sure the hold down screws are TIGHT. This black box controls everything the Injection Pump does. Most people when they have problems with this item notice unexpected stalls followed by harder and harder starts. Yes heat can shorten it's life.
If the Cat pluggs up it won't clear by itself. The opened up exhaust WILL make a difference in performance.
Injectors are mechanical, they work or don't. When one quits you will notice a skip at idle and it gets more pronounced at higher speeds.

[moondoggie]

Good Day!

When I read the posts, a couple things jumped out at me. When the problem appears: 1) boost is reduced, 2) engine runs hotter, 3) increased black smoke. All three of these things will happen if you have reduced air and/or increased fuel. I think the odds of reduced air are quite a bit greater than increased fuel delivery.

My knowledge of these trucks is admittedly limited, but I

[oldmansax]

I keep forgetting to put in pertinent information when I post... must be old age! I can

[moondoggie]

Good Day!

oldmansax: Sorry about the confusion. I was responding to Cowracer

[tom.mcinerney]

Cowracer-is starter/battery cable connection OK?
Cow & Oldmnsx-1.)suggest a temp boost gage to monitor the key aspect of that system.
2.)abrasion of vacuum tube to wastegate solenoid? It would be nice to know mileage on rigs. 3.)Is ignition switch original? 4.)Did you guys read the post by the member in Germany who noticed that his air inlet 'rubber' elbow [i think between air filter and turbo inlet] collapsed under "boost" conditions? I believe he observed the thing sucked together at WOT in Park, creating a dreadful restriction. Good Luck, please report results of your involuntary lab testing program....

[Cowracer]

I wasn't going to make any announcments till I got some more milage on the truck, but I think maybe I stumbled onto something.

#1 The cat was plugged up like a frenchman after a pound of cheese. I now have JK exhaust and that helped overall power across the board, but I still had good days and bad days.

#2 contrary to popular belief, there are many sensors that can go out of range and not throw a code. I have disconnected the IAT, MAP, Coolant temp and the Baro on the firewall in turn, just to see what happens. On each occasion there were NO CODES. But, with the Baro unplugged, I no longer have the low power mode.

I am tempted to say that maybe teh baro was the 'X' device, but...

The weather has not been hot recently so I cant say for sure. As for right now, everthing else is hooked back up, and the baro is disconnected.

Tim

[oldmansax]

Brian: I am quite capable of being confused :confused: enough for everybody!!... All joking aside, the only reason I am hogging Cowracers post is because I seem to have the same problem. I thought 2 trucks to try things on are better than one......maybe.....

Tom Mac: 200,000 on my truck. I need temp boost gauge for sure, just need to get time to purchase & install. I ruled out the waste gate on mine because I physically wired it shut for a test with no change. The ignition switch is original. It doesn

[Cowracer]

the Barometer sensor is mounted on the firewall near the master cylinder. It is identical to the MAP sensor. It is a small black pacakge with the proportions of a deck of cards. I has a single "nipple" and an electrical connector.

I make no guarantees about disconnecting this sensor. I might be doing serious harm to my engine, I dont know...

But what I do know is that my truck 'seems' happier with it disconnected.

Tim

[joed]

I believe the newer trucks (96&up) with the OBD II systems don't have the baro sensor on the firewall. At least my 98 doesn't. I think that function is now controlled by the PCM somehow?

Joe.

[tom.mcinerney]

Oldmansax-congrats on your filter restriction indicator. On the switch....Probably easier to replace than test meaningfully, could test voltage drop across input and all outputs; it has lasted its designed service life. A handful of members have rectified various problems in past year by renewing switch. Both the ignition switch and most harness grounds are nodes where several circuits meet. If the contacts/connections are bad, not all the circuits will receive their share of power at proper voltage. The two most basic steps in electronic troubleshooting(esp digital) are checking the power supply, and reseating the sensitive electronic connectors{disconnect/reconnect plugs}. good luck.

[oldmansax]

Does anyone know if the baro sensor on Cowracer's