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1998 Pontiac trasport - won't rev out on road


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sawyer99
New User

Aug 14, 2010, 1:47 PM

Post #1 of 3 (1357 views)
1998 Pontiac trasport - won't rev out on road Sign In

When accelerating hard pushing the RPM's up the van is limited to just under 4000 rpm as the engine starts cutting out around 3800 rpm or so. At first I thought it was an engine issue and checked things and codes etc. But found Nothing.

I then found that in park the engine is also limited to 4000 rpms as when you rev it up the ecm limits the rpms. So I got to thinking maybe its something with the trans selector switch or something not sending a single to the ecm to let it know its in gear or something. So I pulled the harness plugs off the trans and checked them over, couldn't see nothing bad, so I put it back together. This fixed my problem, never had any codes and I never knew for sure what I did to fix it.

Now its doing it again and this summer!! I checked the harness plugs on the trans and what not but this time it didn't fix the issue.


Has anyone came across this problem before and if so is it something to do with the trans and ecm?


thanks


Sidom
Veteran / Moderator
Sidom profile image

Aug 14, 2010, 9:32 PM

Post #2 of 3 (1350 views)
Re: 1998 Pontiac trasport - won't rev out on road Sign In

Well, I can personally say I haven't run into this type of problem..............yet.

Interesting scenario. It is possible... Just the fact that messing with that harness solved your problem for a while would merit checking it out further. The thing with rev limiters, is when you hit it, it's pretty obvious. I can't feel how it's cutting out so that's where I'm not sure.

If you have access to a scanner with data pids, I would look at the gear selection pid when it's in drive and see what it says. That would tell you real quick...

GM does have problems its connecter. You may want to look at the terminals as see if any look loose. There is an actual test for this called a "pin drag test" basically you get a piece of metal the same thickness as the male pin counter part and insert it into each of the female connectors. The resistance should be the same for all connecter. If one is very loose and barely holds the piece, then that pin needs to be repaired.......


One quick footnote.....On the PD test, you have to be real sure the piece isn't thicker than the pins of the sensor or you will damage the connecter.. While not always possible the best source is an old part like the one you are test..... You can just take a pin off the bad part....


(This post was edited by Sidom on Aug 14, 2010, 9:35 PM)


sawyer99
New User

Aug 14, 2010, 10:36 PM

Post #3 of 3 (1345 views)
Re: 1998 Pontiac trasport - won't rev out on road Sign In

  At first I didn't know what the problem was - fuel, spark mass air flow or what. I did some checks, tried some things and all seemed ok. Then I got on this trans selector & rev. limiter thing as it really seemed like that. Then after I fooled with harness plugs and it fixed it's self I got to thinking hmmm. Actually it started soon after I did the heads on it so I would have disturbed wiring harnesses and what not when I did that job. Good point about checking it with the scanner and seeing whats up with the gear selection now that its acting up again, I'll do that. I have to borrow a GM manual and scanner again as I don't have a good wiring diagram I don't think unless the cheap manual I got from the Auto parts store has something in there to follow. As It would be much easier if I know which wire or wires were involved on the plug. I have heard the that pin thing... we called it "pin tension" back when worked in a auto shop in the 90's. I seem to recall the "tap test" on the old GM ECM's also involving a hammer no less Cooll! Thanks for the input, I'll post back if I get it figured out.



(This post was edited by sawyer99 on Aug 14, 2010, 10:39 PM)






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