97 maxes at 2500rpm/33mph - JeepForum.com
 
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post #1 of 8 Old 07-08-2021, 05:59 PM Thread Starter
Kevoo_11
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1997 TJ Wrangler 
 
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Location: Laporte, Indiana
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97 maxes at 2500rpm/33mph

Hi guys, thanks in advance for any help.

Specs:
97
4.0
Auto - 32rh

Background;
I was driving per usual and after about 25 minutes of being on the road my Jeep began to accelerate on its own and the throttle felt like it was stuck all the way open. It was early, and thankfully there weren't many cars on the road so I kinda blew through an intersection and managed to get off of a main road into a parking lot. I should mention here that I had to ride the break while the vehicle was accelerating in order to keep it under control, which I know isn't good for any engine/transmission. I put it in neutral and pulled the parking break until I was able to get the vehicle to stop. I shut it down and after catching my breath, fired it back up in neutral. It acted like i was flooring it while I wasn't. I assumed that the throttle cable had gotten stuck open somehow, but when I popped the hood I noticed that it was actually the tv cable that had come detached. I popped it back on, and my revving issue got under control, but when I began driving i noticed that the Jeep would top out at around 2500-3000 RPM and roughly 33mph.
At first I thought I was stuck in limp so I pulled the battery negative and tried again - no luck
I decided that I was going to stop screwing around with it and put it in a parking spot - that's when it completely died....At that point I said screw it and had it towed to a local shop that people are generally very keen on.

At the shop:
The power loss/ crank no start was diagnosed as a CPS and the jeep fires right up now. The problem is that it still gets limited out at around 2500 RPM and doesn't go over 33mph.
The mechanic is a pretty cool guy and spent some sizeable time on the phone with me today, and according to him all of the sensors are reading within appropriate values, the cat is not clogged, and the fuel pump is working as it should.

I know you guys on the forum have seen just about everything there is to see with our trucks, so i figured if he can't figure it out maybe you guys can. The only things I can think of are a bad trans/torque converter or that the computer got fried. Any suggestions?

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post #2 of 8 Old 07-08-2021, 06:15 PM
CGrugger
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1936 CJ2A 
 
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Location: Wilmington
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Quote:
Originally Posted by Kevoo_11 View Post
Hi guys, thanks in advance for any help.



Specs:

97

4.0

Auto - 32rh



Background;

I was driving per usual and after about 25 minutes of being on the road my Jeep began to accelerate on its own and the throttle felt like it was stuck all the way open. It was early, and thankfully there weren't many cars on the road so I kinda blew through an intersection and managed to get off of a main road into a parking lot. I should mention here that I had to ride the break while the vehicle was accelerating in order to keep it under control, which I know isn't good for any engine/transmission. I put it in neutral and pulled the parking break until I was able to get the vehicle to stop. I shut it down and after catching my breath, fired it back up in neutral. It acted like i was flooring it while I wasn't. I assumed that the throttle cable had gotten stuck open somehow, but when I popped the hood I noticed that it was actually the tv cable that had come detached. I popped it back on, and my revving issue got under control, but when I began driving i noticed that the Jeep would top out at around 2500-3000 RPM and roughly 33mph.

At first I thought I was stuck in limp so I pulled the battery negative and tried again - no luck

I decided that I was going to stop screwing around with it and put it in a parking spot - that's when it completely died....At that point I said screw it and had it towed to a local shop that people are generally very keen on.



At the shop:

The power loss/ crank no start was diagnosed as a CPS and the jeep fires right up now. The problem is that it still gets limited out at around 2500 RPM and doesn't go over 33mph.

The mechanic is a pretty cool guy and spent some sizeable time on the phone with me today, and according to him all of the sensors are reading within appropriate values, the cat is not clogged, and the fuel pump is working as it should.



I know you guys on the forum have seen just about everything there is to see with our trucks, so i figured if he can't figure it out maybe you guys can. The only things I can think of are a bad trans/torque converter or that the computer got fried. Any suggestions?
What happens when you hit 2500 rpm? Does it just stay there, does lose power to go any higher and just hover around there?

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2005 TJ X: MC 3.5" lift, 33"x12.5" tires, 1.25" Zone body lift, Curry Antirock sway bar.
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post #3 of 8 Old 07-08-2021, 06:28 PM Thread Starter
Kevoo_11
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It doesn't lose power, just sticks at the revs and mph. It revs fine in neutral and park just not in drive
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post #4 of 8 Old 07-09-2021, 12:13 AM
jtec
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some thoughts -
you did not say anything about shop doing a SCAN and checking codes.
A far shot but with a scanner a pushbutton check. Maybe using scanner look at SYNC.
did you try 2nd gear and see if it is limited RPM and speed?

curious -
exhaust was tested with a back pressure gauge ?
fuel pressure same- tested with a gauge? - post PSI.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #5 of 8 Old 07-09-2021, 04:00 AM Thread Starter
Kevoo_11
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The jeep is actually still at the shop. He said he'd like to get to the bottom of it and isn't charging any shop time to troubleshoot. I know that hes scanned it numerous times with the only code being the original cps code that has since been fixed.

As far as psi's he mentioned that it was running right around 49 for the fuel. The exhaust I don't have exact numbers for but it was back pressure tested.
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post #6 of 8 Old 07-09-2021, 05:08 AM
jay-h
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Quote:
Originally Posted by Kevoo_11 View Post
... my Jeep began to accelerate on its own and the throttle felt like it was stuck all the way open. It was early, and thankfully there weren't many cars on the road so I kinda blew through an intersection and managed to get off of a main road into a parking lot. I should mention here that I had to ride the break while the vehicle was accelerating in order to keep it under control, which I know isn't good for any engine/transmission. I put it in neutral and pulled the parking break until I was able to get the vehicle to stop. I shut it down and after catching my breath, fired it back up in neutral....
Some important things about this discussion.

If you have an older vehicle with a key operated ignition TURN THE KEY OFF, BUT NOT SO FAR AS TO LOCK THE WHEEL. Test you vehicle ahead of time but MOST will do that easily.

If for some reason you can't do that, do not '*****foot'. HIT THE BRAKE HARD and hold it to a full stop. Trying to 'slow down' will rapidly overheat the brakes. Jam it down and come to a full stop. You will not do real harm doing that, and it will keep you safe

My toys
'89 Wrangler YJ
'47 CJ2-A

wife's toys
97 Grand Cherokee (ZJ)
87 MB 560SL roadster
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post #7 of 8 Old 07-09-2021, 05:37 AM
jtec
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how about the thought driving in 2nd instead of D - same limiting problem?

If I get Any ideas I will add as they pop up, keep us posted.

When I see the price of OEM I think aftermarket.
When I see the quality of aftermarket I think OEM.
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post #8 of 8 Old 07-09-2021, 07:04 AM Thread Starter
Kevoo_11
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When driving in 2 the same problem persists. Same if you manually shift between 1/2/D.

There is definitely a difference when manually switched between 1 and 2, but no change when 2 is switched to D. I know these things aren't fast, but I can tell that if it's put into D now it accelerates with some more hesitation and even a tick slower than it would have before this problem started.

I'm not sure if it helps at all - but I had the fenders and hood off for paint the day previous to this problem occuring. I didn't really think of that until now because the jeep started and drove as it usually would for 25 or 30 minutes before the problem popped up. I know I pulled the passenger side vacuum reservoir tube but reconnected it. I can't think of anything else that I would have disconnected and forgotten to reattach, though.
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