TPS problems??

OK, it's a 98XJ with close to 140K on it and a recently rebuilt clutch. What is happening is that when I am starting up from a full stop it gets a bit "jerky". Then suddendly it got very jerky, and I was almost considering that my clutch went bad (I'm talking about the point where you almost fully let go of the clutch). Then my chcek engine light kicked in and thrown a code for "too high voltage out of the TPS". I promptly reset the comp after reseating the connector (of all things, I had to unplug the TPS on Sat as I was putting a new gasket under the TB, and while doing so I looked at teh TB and it looked clean). All got better till the next day when it got jerky again and the check engine light tripped again. So I reset it again (I got the code reader with me in the car ) and it hasn't come back for 2 days now, but.... the startup from full stop or near full stop as I'm realeasing clutch in the first is rather jerky (hard to describe it otherwise). So, is it a TPS problem or a clutch problem and the first is the symptom of the second? I got vlose to 15K on the new clutch and till now I didn't really ahve any complaints. I have no complaints once I am rolling, but before I do so it's a whole different story.

BTW, my idle seems to be fine, which I always thought should be an indication of a TPS going bad.

Sounds like your clutch is chirping but with the check engine light on with a code for the TPS I would suspect a problem with that. It might be sending out a bit of an erratic signal which would be noticable when taking off in first (the slightest movement on the gas pedal is noticable then). Check and adjust the TPS or possibly replace if it's not too expensive. Try taking off in second and see what it does. I accidentally do that on occasion.

90NHXJ said:

Sounds like your clutch is chirping but with the check engine light on with a code for the TPS I would suspect a problem with that. It might be sending out a bit of an erratic signal which would be noticable when taking off in first (the slightest movement on the gas pedal is noticable then). Check and adjust the TPS or possibly replace if it's not too expensive. Try taking off in second and see what it does. I accidentally do that on occasion.

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Taking of in second seems to be somewhat similar in behaviour. What do you mean though by "clutch is chirping" ??

Chirping is what I experienced when taking off where no matter what you do with the gas and clutch, short of dumping, it you get that jittery start. It went away finally, but I was told it's from using cheap replacement parts. Not my fault, it was done at a garage when I didn't know any better. Now has 200,000 on her.

90NHXJ said:

Chirping is what I experienced when taking off where no matter what you do with the gas and clutch, short of dumping, it you get that jittery start. It went away finally, but I was told it's from using cheap replacement parts. Not my fault, it was done at a garage when I didn't know any better. Now has 200,000 on her.

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DId you have that from the get go? Or did it show up after a while??

I want to say it happened soon afterwards, but felt great from the shop. Someone said it was like a glazing that happens (I guess like your brakes glaze over). It was quite a few years ago now (like 7 or 8) so I really don't remmeber the time frame. Like I said, where you're shooting a code for the TPS I'd investigate that. Somewhere there's a post for that.

A chattering clutch and a miss-firing engine are two completely different things.

Have someone with some knowledge of cars check it out to determine which it is and then go fix it. Not real hard to tell the difference which it is if you're use to diagnosing stuff.

Anyhow if your computer is saying the TPS is having problems then change it.

mark

Mark Hinkley said:

A chattering clutch and a miss-firing engine are two completely different things.

Have someone with some knowledge of cars check it out to determine which it is and then go fix it. Not real hard to tell the difference which it is if you're use to diagnosing stuff.

Anyhow if your computer is saying the TPS is having problems then change it.

mark

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I'm planning to replace the TPS, but I'm wondering, would a "chattering clutch" or any other clutch issue ever cause the TPS to send out a wrong signal at the wrong time thus resulting in a TPS code in the comp??

Its not your clutch. I'm having the same problem, only worse. After the jittery takeoff, the motor won't rev past 2 grand no matter what I do. Floored or not. I also get the same TPS error code as you. I have replaced the TPS and MAP sensors, compared their voltages to another XJ that runs fine, and still no luck figuring out the problem. If I can't fix it over the weekend I'll take it to a shop. Let me know if you figure it out first, if not I'll let you know what fixed mine. Its not your clutch. Mine's an automatic with the same problem.

SimpleXJ

Kejtar said:

I'm planning to replace the TPS, but I'm wondering, would a "chattering clutch" or any other clutch issue ever cause the TPS to send out a wrong signal at the wrong time thus resulting in a TPS code in the comp??

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NO!


Even xjguy would realize a simple answer like this, but you, noway, not thinking or too much thinking, we'll never understand with you.

hinkley

SimpleXJ said:

Its not your clutch. I'm having the same problem, only worse. After the jittery takeoff, the motor won't rev past 2 grand no matter what I do. Floored or not. I also get the same TPS error code as you. I have replaced the TPS and MAP sensors, compared their voltages to another XJ that runs fine, and still no luck figuring out the problem. If I can't fix it over the weekend I'll take it to a shop. Let me know if you figure it out first, if not I'll let you know what fixed mine. Its not your clutch. Mine's an automatic with the same problem.

SimpleXJ

Click to expand...

Check out the coil.

mark

SimpleXJ said:

Its not your clutch. I'm having the same problem, only worse. After the jittery takeoff, the motor won't rev past 2 grand no matter what I do. Floored or not. I also get the same TPS error code as you. I have replaced the TPS and MAP sensors, compared their voltages to another XJ that runs fine, and still no luck figuring out the problem. If I can't fix it over the weekend I'll take it to a shop. Let me know if you figure it out first, if not I'll let you know what fixed mine. Its not your clutch. Mine's an automatic with the same problem.

SimpleXJ

Click to expand...

Hmmm I don't have a problem with not being able to reach higher RPM's. On my way back from work also I have noticed that the @ idle rpm's would stay high. In any case, I put in new TPS and I'll see what happens.

Mark Hinkley said:

Check out the coil.

mark

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How? I'm used to checking them by reading the resistance between the coil wire and one of the low voltage terminals. I don't remember which one now. I don't if that's how you test an XJ coil, because I've never tested one of these before, and I can't read ohms while its running. I'm not even sure the problem would show, even at idle, because it starts, idles and revs fine until you start driving and actually put a load on the engine.

Any help would be greatly appreciated.
I don't mean to hijack the thread but I'm pretty sure we're looking at the same problem, just different extent.

SimpleXJ

fuel pump? or regulator?

Just a test: Is it only when you HAVE traction? IN other words, what about on slippery surfaces, is the engagement "clunky" when the wheel(s) are allowed to spin? Snow, sand, dirt, etc? Mine (97 XJ 4.0 5 -spd, 231) is often stubborn for the first few miles in the cold. Snow helps, I don't feel guilty about slipping the clutch. I know I have a slowly failign fuel pump or fuel pres reg, and I think it only shows up when cold or with LITTLE OR NO GAS (less than 1/8) or quick starts turnign left. It's weird, Been that way for 1 1/2 years. Sorry little help.