2.5 TJ has hesitation issues

J

Jeep tj Finland

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Helsinki, Finland
Greetings from Finland,
I have a 1997 Jeep Wrangler TJ 2.5. My mechanic is at a loss. We changed the fuel filter, fuel injectors, O2 sensor, distributor cap and rotor, spark plugs....and still it begins to hesitate, slow down as if it is not getting fuel. This usually happens just after 2500 rpm and on a highway at constant speed.

Please help and give me some guidance. What can it be besides all these new parts I have put in.
 
After the problem occurs try to connect a fuel pressure gauge to the fuel rail to verify the fuel pressure....

Do you use catalytic converters in Finland ?
IF you do... consider having a temperature or pressure drop performed between the inlet and the outlet; the CC may be starting to get obstructed.....
 
CharlesHS said:
After the problem occurs try to connect a fuel pressure gauge to the fuel rail to verify the fuel pressure....

Do you use catalytic converters in Finland ?
IF you do... consider having a temperature or pressure drop performed between the inlet and the outlet; the CC may be starting to get obstructed.....
Click to expand...
Charles, thank you for your prompt reply. Yes we do indeed use catalytic converters here. Please clarify what a CC is.
Am on the verge to order a new TPS, ignition coil and distributor pick up coil, accelerator cable...you thoughts?
 
Sorry..... CC is an abbreviation for Catalytic Converter...
Why do you believe the TPS needs to be replaced.... ? IF you decide to replace the TPS; donot go on the cheap with aftermarket sensors. Mopar is the way to go if its available in Finland....
IF the ignition coil were the problem during engine heat; the engine would shut off.... not just hesitate...
The distributor pick up coil that you are referring to... is probably the Cam Position Sensor...
 
CharlesHS said:
Sorry..... CC is an abbreviation for Catalytic Converter...
Why do you believe the TPS needs to be replaced.... ? IF you decide to replace the TPS; donot go on the cheap with aftermarket sensors. Mopar is the way to go if its available in Finland....
IF the ignition coil were the problem during engine heat; the engine would shut off.... not just hesitate...
Click to expand...
Ahh, thanks once again. I do not know if the TPS needs to be changed...am just trying out everything. Mopar parts are hard to come by and then naturally shipping costs, time coupled with a 24% value added tax on the total price is what they do here. Thanks for tip re ignition coil. Am just at wits end....and my mechanic has spent hours on this issue. It it is the CC, then perhaps I will skip all the other stuff and get a new one. Again, many thanks for your input.
 
Do the tests that I suggested to determine if the catalytic converter is the problem before you spend the money on the new CC. IF you determine the problem is with the CC; you could temporarily install a test pipe to bypass the CC while waiting to purchase a new one.
 
5g4pmq.jpg


you may just need a new mechanic
 
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CharlesHS said:
Do the tests that I suggested to determine if the catalytic converter is the problem before you spend the money on the new CC. IF you determine the problem is with the CC; you could temporarily install a test pipe to bypass the CC while waiting to purchase a new one.
Click to expand...
Thanks, yes indeed. Really appreciate your input. br Tom
CharlesHS said:
Do the tests that I suggested to determine if the catalytic converter is the problem before you spend the money on the new CC. IF you determine the problem is with the CC; you could temporarily install a test pipe to bypass the CC while waiting to purchase a new one.
Click to expand...
 
L J said:
View attachment 264575

you may just need a new mechanic
Click to expand...
....yep, that thought too has crossed my mind, but they are hard to find, at least those who will work on a Jeep, albeit easier than the flood of Audi, BMW and Mercedes here....plus electric is the big thing here. And the prices are crazy...as is everything in Finland...my cousin bought a new Audi eTron....price 110,000 euros...(approx 130,000 dollars) craaaazy, and to fix it, good luck
 
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The ignition coils on the 2.5's have a clear tendency to corrode internally and crack over time so take a look at that and I would get a fuel pressure reading.
 
Just to add another train of thought here, when my transmission was rebuilt a while back, the crank position sensor either wasn’t installed properly or was going back. Somewhat similar issue, in that it would suddenly lose power while cruising, but it was intermittent. I don’t know the procedure for testing it, just my experience with a similar issue
 
Jeep tj Finland said:
Greetings from Finland,
I have a 1997 Jeep Wrangler TJ 2.5. My mechanic is at a loss. We changed the fuel filter, fuel injectors, O2 sensor, distributor cap and rotor, spark plugs....and still it begins to hesitate, slow down as if it is not getting fuel. This usually happens just after 2500 rpm and on a highway at constant speed.

Please help and give me some guidance. What can it be besides all these new parts I have put in.
Click to expand...
What fuel filter was replaced, did your mechanic drop the fuel tank.
 
CharlesHS said:
After the problem occurs try to connect a fuel pressure gauge to the fuel rail to verify the fuel pressure....
Click to expand...

I was thinking something along these lines. @Jeep tj Finland, have you done anything like this to confirm your fuel pressure?

I also wonder if the fuel pump could perform fine at lower RPMs, but not be able to keep up with higher demands for fuel at higher RPMs. I don't really know what I'm talking about, so maybe someone else can chime in to explain how wrong I am.
 
SSTJ said:
I was thinking something along these lines. @Jeep tj Finland, have you done anything like this to confirm your fuel pressure?

I also wonder if the fuel pump could perform fine at lower RPMs, but not be able to keep up with higher demands for fuel at higher RPMs. I don't really know what I'm talking about, so maybe someone else can chime in to explain how wrong I am.
Click to expand...
Thank you SSTJ, I do have an extra new fuel pump...however having spoken to several people, everyone thinks it is a lose wire, something not done properly etc....conclusion, easy to fix but hard to find. Coupled with the fact I have done so many changes. Am clueless and frustrated at this point. Hope to find someone who has had the exact same problem (hesitates at 2500 rpm for a few seconds, almost like coughing, jerking). Only happens on highway driving. /Tom
 
Jeep tj Finland said:
Thank you SSTJ, I do have an extra new fuel pump...however having spoken to several people, everyone thinks it is a lose wire, something not done properly etc....conclusion, easy to fix but hard to find. Coupled with the fact I have done so many changes. Am clueless and frustrated at this point. Hope to find someone who has had the exact same problem (hesitates at 2500 rpm for a few seconds, almost like coughing, jerking). Only happens on highway driving. /Tom
Click to expand...
Hi Tom,

Understood. I doubt that my idea would have been right anyway, as I have almost no mechanical background.

To be clear, do you mean that this only happens when you hit about 2500 RPMs at highway speeds? So, perhaps when in 4th or 5th gear? It doesn't happen when you're first accelerating through 2500 RPMs in 1st or 2nd gear?
 
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