Engine/Transmission (1998.5 - 2002) 2001 24 valve missing/surging and failed IVS#2 test

[MarkMullins]

Guys, I need help please. My 2001 got a new transmission around Christmastime. After that it started surging or missing between 1500-2000 rpm's, mostly level ground or slight grade. It does it far worse when i pull my 4000 lb boat. I could swear it was the lockup going in and out but the transmission shop tore into it a second time to double check their work (Great shop). Just a couple weeks ago the owner took me for an hour test ride and tried his best to dump my transmission in a pile on the road and then gave it a clean bill of health. Today I hooked it up to a Snapon Verus Wireless diagnostic tool and ran the APPS test and it failed the IVS#2 test. Well I got on here this evening to research the APPS and found several interesting threads but nothing that would suggest this symptom. I just ordered the Williams APPS sensor from Geno's as an interim measure because I really need to keep my truck in service. (I make my living on the road). A friend who let me use his Verus told me he isn't too familiar with this second generation series of engines and also not the theory of operation on this particular sensor. I wanted to ask here if failing this test means my APPS is bad and/or will this test failure cause my truck to surge on and off like this? One other thing, when I really get into the throttle, it pulls fine and doesn't even seem to have any issues. Thanks for any help!



PS: I run a Superchips programmer. that's it.

 

[sheamc]

I don't know what the IVS#2 test is, but something you said reminds me of a symptom described on Blue Chip Diesels page. The APPS can have a dead spot so to speak, pushing the throttle past that spot and it pulls no problem. You seem to be describing the dead pedal issue I had two weeks ago with the no power/surging I had. I put the tuner to stock and got it home and have ordered the replacement APPS. Check out Blue Chip's page, he has geat info for diagnostics.



Shea

 

[JLandry]

Mark,



The failure of one of the two IVS (Idle Validation Switch) in the TOS (Throttle Position Sensor) will not cause the symptoms you describe. If an IVS truly has failed, it should cause the check engine light to illuminate. The two IVS's are used by the ECM to determine when the accelerator pedal is or is not in the idle position, that's all. There are two switches for safety.



It certainly can't hurt to replace the TPS. Worst case there,s nothing wrong and you'll have a spare. They all eventually go bad.



Questions:



How many miles on the truck?



Does this problem occur consistently every time you drive it or only occasionally?



Do the symptoms temporarily clear up for a time but then come back?



Did it start immediately after the transmission rebuild or was it fine for awhile?



Do you notice it more when the engine is cold or hot?



You describe the symptoms as surging or missing... those seem like different things to me. A surge would be the engine increasing rpm without input from you. A miss would be like one or more of the engine cylinders cutting out... not producing power. Can you please try and describe exactly what's happening in more detail?



Could it be the transmission torque converter is unlocking and locking and you're seeing a change in engine rpm? Or is the rpm staying more or less steady but you're feeling a loss of engine power? If you are seeing an rpm change, how much is it?



When this problem occurs, does the engine respond properly to changes in the accelerator pedal?



Have you tried completely removing the programmer to verify that's not contributing to the problem?



Regards,



John L.

 

[MarkMullins]

Mark,



The failure of one of the two IVS (Idle Validation Switch) in the TOS (Throttle Position Sensor) will not cause the symptoms you describe. If an IVS truly has failed, it should cause the check engine light to illuminate. The two IVS's are used by the ECM to determine when the accelerator pedal is or is not in the idle position, that's all. There are two switches for safety.



It certainly can't hurt to replace the TPS. Worst case there,s nothing wrong and you'll have a spare. They all eventually go bad.



Questions:



How many miles on the truck? 146,000



Does this problem occur consistently every time you drive it or only occasionally? All the time without fail



Do the symptoms temporarily clear up for a time but then come back? No



Did it start immediately after the transmission rebuild or was it fine for awhile? Don't really know since the trans was pretty bad and my attention was on that. I just noticed it sometime after the trans install.



Do you notice it more when the engine is cold or hot? Usually by the time I get to a spot on the road where this happens the truck is pretty warm.



You describe the symptoms as surging or missing... those seem like different things to me. A surge would be the engine increasing rpm without input from you. A miss would be like one or more of the engine cylinders cutting out... not producing power. Can you please try and describe exactly what's happening in more detail? I think "stuttering" might be more accurate. It feels a lot like the TC kicking in and out to me but that has been thoroughly tested and re-tested by the shop.



Could it be the transmission torque converter is unlocking and locking and you're seeing a change in engine rpm? Or is the rpm staying more or less steady but you're feeling a loss of engine power? If you are seeing an rpm change, how much is it? No, see above



When this problem occurs, does the engine respond properly to changes in the accelerator pedal? Yes, the problem is at one spot in the throttle position... you know about 30-50 MPH depending on load... . but always the same pedal position... I used to work on Chevy, Ford and Dodge fleet trucks in the Air Force and this feels very similar to when their TPS was dead spotting.



Have you tried completely removing the programmer to verify that's not contributing to the problem? Yes, not the problem.



Regards,



John L.

Thanks very much for the info and questions. The reply above yours about Blue Chip Diesel was helpful as well. I read his diagnostic info and he has a nice paragraph concerning this issue. It points to the APPS for sure. I went ahead and ordered the Williams unit last night from Geno's to have one on hand. I hope it is a fix.

 

[bcbigfoot]

MarkMullens what frequency is the stutter when it occurs, example: 2 times a second or maybe once every 3 seconds. I have a very similar issue with my truck, a new apps didn't do the trick, the frequency of the stuttuer with my truck is approx: 3 times a second. My issue is not with the trans.

 

[MarkMullins]

bcbigfoot, turns out mine did need the APPS. I got it in this morning and installed it. It runs fine now and I cannot duplicate the previous issues.
What it was doing was very similar to the transmission locking and unlocking. Some of the guys on here who are stronger in driveability than me might laugh at that but that's the best description I have.
It felt like the truck was "missing". I cannot say what frequency it had but mine only happened at one spot on the throttle range of movement. I had a Snapon Verus scanner and one of my old troops watched the o-scope readings while pushing the pedal towards the floor with the key on. not running. it took hiom 2 minutes to pinpoint it with the scan tool.
If you read on Blue Chip Diesel's diagnostics page he has a nice bunch of info there. Good luck!

 

[MarkMullins]

Well, I spoke too soon. The truck seemed to be fine when I test drove it. I ran it about 25 miles. Next day out working the truck was doing the same thing. I have exhausted all my resources and knowledge trying to pinpoint this problem and no luck. I don't like throwing parts at problems but my APPS was clearly failing tests.
Could I have a bad VP-44 computer, or something else? I am really stumped, and at this point, considering dumping the truck. I do not have the time to be chasing this problem with my job requirements.

 

[JLandry]

Could I have a bad VP-44 computer, or something else?

It sure sounds like it could be the VP44.



Usually a problem with the TPS will be fairly consistent whereas problems with the VP44 can be quite intermittent.



Don't give up... a new truck will cost you a whole lot more!



John L.

 

[MarkMullins]

Well, I haven't had a lot of internet time since replacing the APPS in my truck. But its stumbling or stuttering or coughing... I am not sure which description fits. The truck feels exactly to me like when the transmission kick sout of gear and back in. Its like an instant throttle let up and then back on in an instant. This is extremely frustrating and it is killing my fuel mileage. I drive it harder in an effort to reduce the issue. Any further help from some of you experts on here would certainly be appreciated. Thanks.