View Full Version : Lost power
I have a motorhome from 96 that only done 20 000 km (12 000 miles). Only driven it 4 000 km myself since bought it last autumn. It suddenly start loosing power, estimate around 20% less. But that is much on a heavy motorhome. I replaces air and fuel filters, lift pump is working well. There is no smoke from exhaust. I got codes P0236 and P0237 suggesting a turbo/wastegate problem. But there is no black smoke or other sympthoms that should show if I have low pressure. Turbo is fine, wastegate seem to work. Still have to get a way to measure the pressure to confirm that. Don't think it's a blocked exhaust system.
Any thoughts?
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P-O
welcome
When was the last time the fuel filter was changed ???
Fuel flow constriction can really chop the power and in a hurry.
Missy
Hi Missy,
I changed fuel and air filters 2 days ago, that was the first thing I thought of. I will try find a gauge to measure turbo pressure this week. A loose part in the silencer could cause the same problem, but don't feel like crawling under to take it apart...:(
Could there be a dried and cracked bellow in the waste gate actuator? The rod is feeling very sloppy when engine is not running, but seem to work when I start. Vehicle has been sitting unused for most of it's life.
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P-O
Check the vacuum to the waste gate actuator, it should be about 16" HG with engine running.
Check the vacuum at the vacuum pump too, it should be 26"hg and steady. If the needle wobble wildy then the pump is shot.
Keep us posted
Missy
Made a temporary connection to a pressure gauge. When starting with cold engine pressure is going up to 0,5 bar around 1900 rpm and drops off above. After driving 5 km and engine reaching operating temps, pressure suddenly drops to zero. Looks to me like an electric fault in a component when it gets warm. The drop was instantly from pressure to zero when I was watching the guage.
Don't have a vacuum guage near to test, but is that nessesary now?
I been reading the service manuals, 2 heavy books. Not the easiest to follow, especially when I don't have the diagnostic tools. Any further suggestions appreciated.... I'm going for a 1 000 km trip in a few days and don't fancy limping along without turbo pressure :mad:. I have taken the MAP sensor off and measured resistance. No change when putting a bar pressure on it.
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P-O
I have taken the MAP sensor off and measured resistance. No change when putting a bar pressure on it.
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P-O
That's not a valid test. Apply 5 volts to the sensor. The output is voltage proportional to the pressure.
If you're going to fire the parts cannon at it, change the wastegate solenoid first. before you do that, though, check all the connectors
Tried the MAP sensor better. Applied 5 volts to it and checked what came out. There is 2,4 volts without pressure, and 3,5 volts with 0,5 bar on it. Took the vehicle for a test run and same thing happened, only earlier this time when engine was warmer. Sudden drop of pressure.
Update: bypassed the solenoid, still no turbo pressure. So pump or actuator bad. Will go to town buy a vacuum guage tomorrow. And throwing parts at it is not a valid option. I'm in Europe and parts here usually comes through GM importer at a price I wouldn't consider... So parts are a week away from US dealers like RockAuto. That means I have to make sure I really order the right part.
Anyone taken a pump apart? What could cause this intermittent failure... Really don't fancy crawling under the motor home trying to get that pump out.
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P-O
After it drops out, if you let off the throttle then come back in gradually, does it make boost again or not? When it drops out, is the boost increasing or decreasing right before?
I cannot imagine a failure scenario for the actuator where it would work until hot.
Found it! Was the solenoid after all. I didn't manage to bypass it properly first time, there must have been a leak. Now with the vacuum gauge I could see what I was doing. Pump is doing 24" Hg steady.
Thanks Guys for the support!
Now, should I go for the turbo master instead? We have similar emission control as California, would there be a problem if I also do the Heath computer upgrade too?
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P-O
Found it! Was the solenoid after all. I didn't manage to bypass it properly first time, there must have been a leak. Now with the vacuum gauge I could see what I was doing. Pump is doing 24" Hg steady.
Thanks Guys for the support!
Now, should I go for the turbo master instead? We have similar emission control as California, would there be a problem if I also do the Heath computer upgrade too?
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P-O
I'm dealing with the same issue and believe the solenoid is at fault on my rig as well. I have also considered going with a turbomaster and computer work but the computer isn't in the budget right now so I'll probaby just change the solenoid. Let me know how it works out. Oh, I just passed a smog check here in California. If I get a chance I'll stop back by the shop and ask if the computer programming will cause it to fail.
6.5 Detroit Diesel
05-10-2011, 09:21
I'm dealing with the same issue and believe the solenoid is at fault on my rig as well. I have also considered going with a turbomaster and computer work but the computer isn't in the budget right now so I'll probaby just change the solenoid. Let me know how it works out. Oh, I just passed a smog check here in California. If I get a chance I'll stop back by the shop and ask if the computer programming will cause it to fail.
how did you pass a smog check with a gutted out cat?
how did you pass a smog check with a gutted out cat?
The test probably doesn't look for NO2
DmaxMaverick
05-10-2011, 21:09
The test probably doesn't look for NO2
It doesn't. The test consists of a visual inspection (all listed components according to the VIN must be present and "appear" to be working) and a happy computer. Smoke will fail.
how did you pass a smog check with a gutted out cat?
It's mostly a visual check and check for computer codes. $50.00
I'm also wondering if anything did get done to the cat when the engine was changed 50K ago. I had mentioned doing it but I think we ran out of time. Nothing looks disturbed at the cat. I might wait until I move back to the midwest before doing any mods or upgrades just so I don't have to worry about it. Hopefully a move will come in a year or so.
If you go wityh the Computer upgrade, you need a free flowing exhaust system.
The turbo master and the computer upgrade (reprogram) allow for more boost and more fuel (more power) and the stock exhaust system will be way to restrictive.
If your up and going OK now, wait until t\you can add the exhaust upgrade.
You can do the exhaust without doing the TM and computer, then add afterwards.
check to be sure these components will not violate Cali Smog Laws.
DmaxMaverick
05-11-2011, 07:36
If you go wityh the Computer upgrade, you need a free flowing exhaust system.
The turbo master and the computer upgrade (reprogram) allow for more boost and more fuel (more power) and the stock exhaust system will be way to restrictive.
If your up and going OK now, wait until t\you can add the exhaust upgrade.
You can do the exhaust without doing the TM and computer, then add afterwards.
check to be sure these components will not violate Cali Smog Laws.
They will. Any of the above. The visual inspection requires all of the OEM emission system equipment to be present and working (or appear to be working). Computers are more complicated. The best option is to obtain a core PCM and have it programmed (for testing, diagnostic, or off-highway use only. It is unlawful to modify or disable emission system equipment in any way). Swap in the OEM during the test. The converter must "appear" to be present. The actual function (exhaust gas composition) isn't tested.
a5150nut
05-11-2011, 19:47
DMax,
Which counties are they testing in?? I'm in Santa Clara County and have a 94 and haven't had to test so far. Knocking on wood. . . . Maybe I need to register in Lasen County to be safe. Or am I out of the year range or 8600 gvw get me clear ?
DmaxMaverick
05-11-2011, 21:22
So far in CA, it's for 1998 models and later. Nothing for earlier models.
No cat for 8 years..passes every time. CT's test is not a joke either.
I have done 500 km since bypassing the solenoid. Manifold pressure stay around 3-4 psi when full vacuum on the wastegate. Haven't felt any difference in driving, and fuel economy is exactly the same.
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P-O
If you go wityh the Computer upgrade, you need a free flowing exhaust system.
The turbo master and the computer upgrade (reprogram) allow for more boost and more fuel (more power) and the stock exhaust system will be way to restrictive.
If your up and going OK now, wait until t\you can add the exhaust upgrade.
You can do the exhaust without doing the TM and computer, then add afterwards.
check to be sure these components will not violate Cali Smog Laws.
There isn't a good way to upgrade the exhaust and keep the cat is there? I mean to have 3.5" or 4" to the cat and restrict it there doesn't seem like it would accomplish much if anything. And a 4" cat has to run a bundle of cash.
Yukon6.2
05-18-2011, 08:13
Hi
You could gut the cat.
Or if you are a fab/welder you could make a 4" gutted cat.Find one that the body is big enough to run a 4" pipe through it.Gut it ,weld the pipe through it and install.Make it look like it was a factory job and install.
Or mabey one from a newer truck may be a choce if you want one that is functional.
Thomas
I did the change to Heath Diesel computer upgrade for max torque and the manual turbo boost control. It worked very well, got plenty more power at low rpm and slightly better fuel economy. Even when using the extra power on a heavy motor home most of the time I get better milage than before. I'm doing 12-13 mpg going 55 mph with the 15.000 lb vehicle. :) Been on a trip through Europe and could keep up with most of the heavy trucks now.
Went through the annual vehicle check with a K value of 0.4, compared to 0.8 before the upgrade. This is with std exhaust and water pump. It's running warm faster now when going uphill until electric fan kicks in. Don't really feel an upgrade there is nessesary yet. Got a max turbo pressure of 14 psi.
I'm happy with the result, well worth the money.
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P-O
There is an outfit called " Frozen Boost" that makes Cat Look a likes that are nothing but a cat shell with a pipe that runs through the shell.
These look like the real deal, but will get rid of the issues of a constipated Kitty.
These are stainless steel I believe and look very nice
Here is a link to their site http://www.frozenboost.com/
Look under exhaust parts.
They make one thats 3 inch or you could use a couple Y pipes and install 2 of them if your worried about flow.
A 3 inch down pipe through the "CAT" then up to 3-1/2 or 4 inch on out the back and your set, no more issues.
Hope this helps
Missy
Thanks, interesting site... But I haven't got a cat, it's not needed here on so old cars. Forgot to mension I changed the fuel pump too. Needed better fuel pressure to reach 14 psi boost.
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P-O
phantom309
11-27-2011, 20:29
nice heavy spring works the best,.:D
nick
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