2.5 TJ has hesitation issues
- Thread starter Jeep tj Finland
- Start date
Indeed, like me, no mechanical experience, but I do know when something is wrong...sort of like if you have a dog, you know something is not right, but the dog cannot tell you what it is. This is really becoming a PITA. So to recap this is what I have changed in last 3 weeks: Fuel filter, spark plugs, dist cap/rotor, fuel injectors, TPS, IAC valve, O2 upstream. Have driven all the gasoline out to renew with 'fresh' gasoline.
I hate throwing parts at Jeeps so do you know anyone with another 2.5L that you could borrow a Crankshaft Position sensor. They are known to fail slowly but usually it stops the engine temporarily rather then your issue.
Thank you TJ4Jim, Jeep Wranglers are not that common in Finland. And I am a member of the Jeep Club here, but again, no input from there. That said, I just ordered the CPS from Spain (probably Crown product). Thus, that is my next upgrade will do, but have to wait until next week since it is on a truck traveling through all of Europe to get here. br Tom
If it's a Crown try and cancel it. The sensor really needs to be a NTK as most will tell you they just do not perform properly or at all.
Sorry for next t being clear. I will be driving at a constant speed in 5th gear and suddenly the engine hesitates as if no fuel, “coughs” hesitates....then goes as normal and after a while repeats. This happens after 25k rpm. I guess when engine heats up. It does not stall, just hesitates. Does not happen when changing gears. Thanks Tom
Let's all keep in mind that I don't know what I'm talking about, but this reminds me a little bit of the behavior I experienced, years ago, when my exhaust manifold was cracked, and my O2 sensors were becoming damaged. Anyone else know whether that's anything that Tom should look into?
Edit: I see now that Tom already checked the O2 sensors. What about the manifold itself?
Edit: I see now that Tom already checked the O2 sensors. What about the manifold itself?
Will check tomorrow, thanks. And if this is the cause, will post details for future ref
Also, if you have a minute, perhaps update your original post with any clarifications, or updates, that have come up in the thread so far. That way, when others visit the thread, they don't get scared away by having to read through all the pages of comments.
And, you've probably already done this, but I just searched the Forum for "hesitation" and several others have experienced similar issues before. Some results are below:
https://wranglertjforum.com/threads/97-tj-4-0-rough-idle-and-hesitation.21802/https://wranglertjforum.com/threads/2006-4-0-tj-hesitating-running-rough-when-under-load.16213/https://wranglertjforum.com/threads/hesitation-on-immediate-full-throttle.29834/https://wranglertjforum.com/threads/hesitation-issue.27181/https://wranglertjforum.com/threads/1997-jeep-tj-4-cylinder-hesitation.14935/
To SSTJ et al. Problem solved (for now). Long story short, my 1997 2.5l Wrangler TJ began to slow down when there was a small incline on the highway...note this is always highway driving around 80 kms/h (about 50mph/h)...RPM around 2-2,5K. I thought hmmmm, pressed my pedal down to the floor and eventually when the highway incline leveled off, all was fine. Please be aware this is after the engine is warm and it did not happen all the time.
Then my TJ started to hesitate, as if not getting fuel, bucked and hesitated...again highway driving. So the unmistakable boob that I am...and this happened several times, so I threw money at my TJ. Replaced fuel filter, spark plugs, 02 sensor upstream, fuel injectors, TPS, Idle Coil, Dist Cap and Rotor. Drove the vehicle until no more fuel to put in 'new' fuel...60 liter tank....100 euros (118 dollars). Did the pressure test, then did diagnostic test....the mechanic deleted the four alarm codes (they were not showing on the dash). I asked him what the codes were, but somehow got lost. So we did it gain.
Conclusion: O2 sensor downstream needed to be changed. That's it folks. So if you vehicle is hesitating like mine, sure do regular maintenance, and clean Idle Coil, TPS and anything else...but focus on the two O2 sensors. Well that is for now, who knows what will pop up again. Maybe the time has come to sell my TJ, and the person who buys it will get a mint car for a 1997 TJ....Thank you all for input.
Then my TJ started to hesitate, as if not getting fuel, bucked and hesitated...again highway driving. So the unmistakable boob that I am...and this happened several times, so I threw money at my TJ. Replaced fuel filter, spark plugs, 02 sensor upstream, fuel injectors, TPS, Idle Coil, Dist Cap and Rotor. Drove the vehicle until no more fuel to put in 'new' fuel...60 liter tank....100 euros (118 dollars). Did the pressure test, then did diagnostic test....the mechanic deleted the four alarm codes (they were not showing on the dash). I asked him what the codes were, but somehow got lost. So we did it gain.
Conclusion: O2 sensor downstream needed to be changed. That's it folks. So if you vehicle is hesitating like mine, sure do regular maintenance, and clean Idle Coil, TPS and anything else...but focus on the two O2 sensors. Well that is for now, who knows what will pop up again. Maybe the time has come to sell my TJ, and the person who buys it will get a mint car for a 1997 TJ....Thank you all for input.
Glad you got it sorted!
For a noob like me, can you tell me more about the "two" O2 sensors? What do you mean when you describe one as "downstream". I see you had already replaced the other one, in your original post.
For a noob like me, can you tell me more about the "two" O2 sensors? What do you mean when you describe one as "downstream". I see you had already replaced the other one, in your original post.
Sorry for not being clear. Yes I had the upstream o2 sensor changed (before the catalytic convertor close to engine). Neglected the o2 sensor downstream (after the catalytic converter). There was the problem...at least until now. Note 97 TJ has only two o2 sensors. Time will tell