Engine/Transmission (1998.5 - 2002) Run away throttle

[spikemc]

About a month ago I had what can only be described as a run away throttle, I shut the engine down at approx 2800 rpm, let it sit for a minute or so and re-started and had no problems for the rest of the trip. This afternoon same run away problem, this time it shut itself down and it took 3 tries to get it re-started, the only code is P-0236 which has something to do with the turbo circut. I checked with the local diesel shop with no help. Other than this the truck runs like a champ, any ideas. The APS was replaced with a Timbro at around 127,000 miles, I'm at currently 184,500 miles. I was thinking the ECM but could the APS be hanging up ?



Thanks in advance, Skip

 

[BigPapa]

Check your intercooler tubing between the turbo and intercooler for oil. If the turbo's leaking oil it will cause a runaway. It may be leaking just enough to do it every so often but not enough for a full fledged runaway, YET.

 

[SierraRam]

When you say run a way do you meen the rpm increased and you turned the key off and it continued to run? If so you are introducing oil and/or fuel into the intake track. If you turn the key off and it shuts down I would look at the APPS again.

 

[spikemc]

When you say run a way do you meen the rpm increased and you turned the key off and it continued to run? If so you are introducing oil and/or fuel into the intake track. If you turn the key off and it shuts down I would look at the APPS again.

The first time it happened I was concerened with over revving the engine so I shut down at that point the engine did shut down and did not continue to run. The second time I allowed the engine to run for about a minute at that point it shut itself down and did not continue to run. So in the real sense of the term "run away" it did not contine to run on it's own with out the ignition turned off. One other detail, this happened both times imeaditly after slowing down then adding throttle after coming to a stop which is why I was thinking the APPS may be hanging up. The turbo and intercooler boots were both just changed, but it would be a good idea to rule out anything in the intercoole circut.

Thanks for the help I'll keep you updated, Skip

 

[cerberusiam]

As a guess you are going to get a P0216 code at some point. If the engine shuts down with the key its fuel that is causing the rev. That is usually coming from the IP and that means another VP-44 on its last legs.

 

[spikemc]

As a guess you are going to get a P0216 code at some point. If the engine shuts down with the key its fuel that is causing the rev. That is usually coming from the IP and that means another VP-44 on its last legs.

I don't disagree, but this would be the third IP. After the second pump failure I installed the Air Dog and have had steady fuel press between 14 and 16 psi. There are NO injection pump related codes so the idea is possible but I would think I'd be seeing other IP failure related issues, like dead pedal. Like I said it's possible but could the culprit be in the MAP senser since I'm getting the 236 code. I removed the MAP sensor, cleaned it reinstalled it and it's still showing the code even after I cleared the codes. I'm not a genious at trouble shooting electrical components but I'm trying to find out how to diagnose the MAP sensor before pulling the trigger on a new one. As an after thought I talked to Cummins Northwest they were reluctent to take guess without seeing the truck, the only comment they made was be carefull over thinking codes since there could be one not showing up but still causing a problem.

Thanks, any and all help is appreciated, Skip

 

[cerberusiam]

I have yet to see a MAP code casue it to over fuel, but, that is not definitive either. It is entirely possible the high MAP reading is causing the ECM to add fuel.

Normally, the MAP high too long derates the whole boost map and it goes to a default mapping with a code. Unless I had the code that actually interprets the sensors readings and tracked the logic I would bet against it just adding fuel.

If the MAP is showing a code replace it and go from there, much cheaper than a runaway engine or the truck jummping a divider or running a light cuz you can't stop it.

 

[Bob4x4]

Checking the accuracy of your map sensor is relatively easy since you have a boost gauge installed. Connect a scanner and have an assistant watch the boost shown while you are watching your gauge during a test drive. Your quad box may be failing causing the code . Normally when the boost sensor itself fails you will have low power till the rpm hits about 2k rpm. You can check your sensor wiring circuits to be sure it has a good ground,5 volt supply and that the sense wire is not open or shorted to ground or 12 volts.
If it were mine I would also disconnect the throttle cable from the apps,move the sensor through it's travel to be sure of no binding and that the return spring was functioning properly. Move on and by hand feel the cable to verify it has no binding

 

[Diesel Gunner]

My bet is that the XZT+ is causing it. I have one also and have had this occur on rare occasion. Take the box out and my bet is that it will not do it. I have reloaded the softeware and it seems to go away for quite a while and then mysteriously come back. Mine however will just start a slow increase in RPM and I have always been able to shut it down before getting anywhere near high RPM.

 

[spikemc]

Thanks gentlemen, Bob; I'll go through the checks as suggested, Gunner; when you say "reload software" are you referiing to updating the module ?. Thinking about the rise in RPM, it does build slower, it's not a real fast increase in RPM.
Thanks again, Skip

 

[Diesel Gunner]

Yes. I have reloaded the software and that seems to help. I am no expert but I think that the files may become corrupted over time for various reasons. Perhaps the unit is not shielded from outside frequencies well enough or voltage changes in the trucks system cause it? IT is easy enough to try and see if it makes a difference.



I bought the XZT+ because it was a few bucks less expensive and I did not need all of the xtras that come with somewhat more expensive units. But, if I had to do it all over I would definately consider spending a bit more.



Good Luck

 

[spikemc]

Gunner, looks like I'm going down the same road as yourself, unplugged the Quad and the 236 code went away without needing to clear the reader. It does still show a yellow light whch means there may be something lurking around which may mean a trip to Cummins Northwest which the truck is in need of anyway for it's 200,000 mile check up. I'm updating the module, I'll give it a go tomorrow morning and see how it does. I was given the Quad in exchange for some work I did for a friend , but I agree I don't think this would not have been my first choice in add ons.





Skip

 

[Diesel Gunner]

Has reloading the software in the module helped?



Anyone else have any suggestions on this problem? Mine has taken to idleing just a tiny bit high after being on the hiway on cruise control and then the exhaust brake won't work unless I shut it off and restart it.

 

[spikemc]

Gunner, short answer I'm not sure. But here is the update and plan, Monday I clearded the 236 code, drove into town, engine light came on, checked codes and it showed a 237 code. Shut off the Quad and the plan is to leave it turned off untill the new MAP sensor arrives. I'll probably leave the Quad shut off for a couple of tanks of fuel to verify mileage and see if the high rev problem shows up. Then I'll run with the Quad turn on the power setting and see if the rev problem shows up in that condition. I'm and old submarine machinist mate and need to have things run as close as perfect as possible. When I discussed this with my better half she is not comfortable with a phantom problem lurking around in the truck when it's something that could be considered a safety issue. Money is a little tight but she is on the same page as me about gettiing this resolved and it looks like an Edge juice with the CTS screen will happen this next spring and I'll send the Quad off to another life. The truck will be due for it's 200 k sevice with Cummins Northwest so that may really get to the bottom of whatever is causing the rev "thing". We go on vacation to places along way from anything or place and as I mentioned we really need the truck to be close to perfect as possible.

Thanks for your help and concern, I'll keep you posted, Skip

 

[Diesel Gunner]

I will be interested in hearing how things go.



Well, the smog nazi's here in CA said that I can drive it for another 2 years yesterday (Smog Check) so as soon aI got home I plugged the box back in and it sure runs better again. We went fishing yesterday afternoon and when I started the truck to come home it high idled like it supposed to to warm up. I have not had it on the hiway for any distance to see if it will high idle and keep the exhaust brake from working but will find out tomorrow when I go to work. I know what you mean about wanting everything to work correctly as we get quite a good distance from civilization with ours also.



HAs anyone else encountered the high idle that keeps the exhaust brake from working? What was the fix?

 

[super38]

Mine did the samething back in 2009, almost ran over a family at Wal-Mart when it suddenly took off. Removed the Quadzilla and never had the problem again. Took box over to Quad in Fort Worth and as you can expext they did nothing, still have it in a box somewhere and there is no way I would ever run the XZT or any of their products again after the way I was treated.



https://www.turbodieselregister.com/forums/showthread.php?212960-Quadzilla-XZT-causes-runaway



JD

 

[spikemc]

OK folks, received the new MAP sensor and was talking to the deliveryman who was in the diesel repair biz, apartently there are hard codes and soft codes. The code reader shows the hard codes and this is what is seen when I read the MAP codes, the yellow light is still lit which may mean a soft code lurking somewhere in the computer. I was able to clear the 236 and 237 codes which also cleared the 1693 code that showed up. The truck seems to run smoother but have not been able to get out and really give it a test. Time will tell on the over rev problem, Quad will still be off for now and I still plan on turning it back on after a couple of tanks of fuel to see if it was part of the over rev problem.