ALright guys, I appreiciate all the help I can get on this one. Sorry for the MONSTER post, but this time I've gotta be descriptive...

My car had been hesitating, sputtering, and backfiring when pulling out from a dead stop or with a load (like on a hill) at low RPMs. My initial thought was that I had stretched the timing chain, but my compression was fine on all the cylinders (180 psi +or- 5psi). Checked the timing... still at 2* BTDC. I replaced the plug wires because I knew my MSDs were arcing and cleaned and re-gapped the plugs (#8 plug was black with carbon). This made very little change. I replaced my cap and rotor with the old one, just to see if that was it, it wasn't. The coil was new as of last summer so I've kinda skipped over that one too.

So I pulled codes 23. (MAT or TPS) and 42. (ESC or ignition module) out of it the other day. I replaced my ignition module and, for good measure, my O2 sensor while I was at it. I haven't replaced the TPS yet because I was under the impression that it is for emmissions purposes only. Now the backfiring is gone, but she's still not quite all there. There is still hesitation when accelerating from a dead stop and it "chugs" a little every now and then on a hill. Whatever is wrong, you can hear it at idle, but just barely. Every now and then (when it makes the sound) it will drop 1-200 RPMs but recover just as quickly. I know this is where WinALDL would come in handy, but I don't have the luxury of having a laptop to log data with and the cheapest shop in town wants $55 an hour to diagnose the thing (pending that they would find it at all). That's money that could be well spent on sensors or an ECM if needed.

Well, that's it, and I haven't gotten any codes out of it since. Everybody is encouraged to reply because I'm out of ideas and nearly out of cash.

 

Guess what! I had similar problem. I've replaced wires and all sensors and skip the TPS like you did. Car got better but not all problems were solved. SES light comes on every now and then. Car hesitates, Can't even shift to 5th gear because of lack of power. Finally I replaced the TPS just because I had an extra one from another car. To my suprise my car really woke up. No more SES light, no more hesitation, my shift light even worked and I can now shift to 5th gear and won't feel the lack of power (that made me very happy), Gas mileage is now alot better....

TPS:hail:

 

Ok, I know I'm gonna sound ssssssooo stupid, but my car's sort-of doing the same thing. What is a TPS Sensor, and where is it? When my car started doing some of the same things, I thought it was a dirty fuel injector or something. Also, a thought, could it be a O2 sensor?? Forgive me...I'm still learning.

 

TPS is your Throttle Position Sensor (located opposite the throttle linkage on your throttle body). I have heard of an O2 sensor giving people problems similar to ours, but I replaced mine and it didn't stop the symptoms.

Thanks for the reply RS91. I'm leaning more and more toward the TPS, but I would still like more input from whoever can muster it. No SES light so far... In the morning I'm going to go check to see if there are codes again, but I don't really expect any. These are the possibilities as I see them (lemme know if you can think of more).

1. Still haven't done anything about the code 23 so I could have a bad TPS or MAT sensor.

2. The ESC is bad. (or possibly knock sensor, but I doubt this because I have not gotten the code for it... 43 right?)

3. My coolant temperature sensor is bad and the computer is too stupid to realize it.

4. My CAT is clogged worse than a sewer drain in Boston after a downpour.

Like I said, anyone that can help me identify this... PLEASE DO! I need all the information I can get. On my way home from work tonight I stood on it and nothing. I mean, it accelerated, but NOTHING like it used to. There is just nothing there all the way through the powerband. The problem has got to be electronics related because it runs okay when the car is cold, before the computer comes out of warm-up mode.

Thanks again,
Harry

 

I'm having the same symptoms/problems. When my car warms up it's a pig and sucks huge amounts of gas.. All this after my cam swap.......hmm....

 

Go and run the car for a nice 30 drive, see if SES comes on or after if you can pull any codes still. If the tps was bad, the car should rev irradically at idle(I would think, mine did). However, it could just be on the out.

Very well could be the water temp sensor, since you said it works (or seems to work fine when cold). As you know, when the car warms up and goes into closed loop, it runs off the water sensor, not the 02, which would lead me to believe thats the problem. I had one go bad, my computer never picked it up. It just fouled the SES light to a TPS(like in your case).

Theres no gaurantee that changing the water temp sensor will work, but hey for $20, it isn't gonna break the bank, and probably needs to be replaced soon due to age anyway.

Let me know if any other coditions exist that you haven't posted if this doesn't work.

It sounded at first to me like a plugged up cat, but when cold it still wouldn't be normal, if that was the case.
GOOD LUCK

 

Its probaby not the ESC, because that should trip another code ...48? I can't remember the number. Somewhere around that. Also, when cold it wouldn't work well too.

 

Here we go for another installment...

Thanks for all the help to both RSCameroGuy92 and RS91 but today I replaced both the CTS (yes, it was the one at the front of the intake manifold) and the TPS with no change and still no codes to speak of (both were only $30 and they probably needed to be replaced anyway). I also found out that the ESC module would be $70 new or the MAT sensor would be $30.

Tomorrow I plan on gutting the cat and running a straight pipe through it so I can pass visual inspection. It is the stock cat so there is no way that this could hurt, but I don't really see this as being the source of my problems. As I've said, the car appears to run fine for about the first minute when cold, then it begins the sputtering. It's almost like a miss, but one that only happens every couple hundred revolutions. The exhaust kinda smells rich.

Here are the questions I have now:

1. Is it possible that a bad MAT could cause these kinds of problems? I've heard of people just leaving them unplugged before without problems so until this point I've ruled that out.

2. If a spark plug is going bad, can it work intermittantly??? I've never heard of one doing this before, but if they can then that could be it.

3. Will the computer still give a code 12 even if it isn't working properly?

I'm going to take it out for a drive again tonight to see if I can get any codes to come up.

 

A little more update...

Just got back from another 35 minute drive. Still no codes, but IT BACKFIRED again. Backfire, detonation... whatever it was I DON'T LIKE IT!!! I was going about 60mph, let off the gas for a couple seconds then put it to the floor and *POW* three or four times right together. oh yeah... and after all that, it idled like crap while in gear.

 

I got your PM, sorry I'm clueless on this one.

 

well, the cat is now gutted and a straight pipe installed inside it (so I can pass visiual inspection). This however did not help what's going on. I only have 3 real options left... plugs, ESC, and ECM. SO tomorrow I guess it's plugs for me. If that's doesn't work then I'm off to the nearest pick-a-part for the rest. I'll keep you guys updated just so anyone with this problem in the future can figure it out.

 

Mean,

The ESC can be bypassed easily if you suspect it is causing uncontrolled timing fluctuations. Just disconnect the bypass connector and test drive the car. You may set another error code as a result, but at least it won't be unexpected.



In a related matter, what is your base timing setting? Have you inspected the pickup coil and reluctor lately? How is the distributor cap and rotor? New spark plugs are always a good idea if you suspect an ignition problem, and yes, they can fail intermittently.

Incidentally, the TPS is not simply for emissions purposes. It is what send the throttle position information to the ECM so it can calculate the correct fuel mixture and spark advance depending on your driving conditions, as well as inputting data for TCC lockup and a few other items.

Keep us posted...

 

Sounds like you timing is off. Did it backfire through the carb or the exhaust? The carb would mean that its retarded(sorry, I don't mean dumb)and the exhaust would mean advanced too much.

If that's not the case, pull the plug wires one at a time and set them near a ground while the engine is running. Make sure that you can see the spark jump from the wire to the ground. Check all eight that way.(Wear some form of rubber gloves and no metal to prevent shock, as this is not the right way to check spark, but it works).

As for the spark plugs, if you can't remember the last time that they were changed, then its probably a good idea to change them anyway. I change mine every spring when I get the car back out of the garage(I don't let her see snow and road salt). But supposedly, you don't have to that often.

If the ECM was bad you should get a trouble code I think its 51?
Try unplugging it and seeing if that changes the idea at all(theoretically it should get worse)
That is the plug pictured above. The wire should be grey/brown with a stripe(it think its black)

 

"hesitation" usually means ur running lean. check the 02. if the car is hooked up to one of those snap on scanners....check to make sure the mV for the o2 is changing. if not tha is more than likely ur problem.

 

If the O2 was going bad, it should show the SES light and shoot some codes, right?

 

Well, it may be a fluke, but for now my car is running right. Today I replaced the plugs and what do you know, no hesitation, no backfire, idles 100% better, even spun the tires on the 2-3 shift. With the way it was acting I would have never guessed, not in a thousand years, that it was the plugs. I just replaced the damn things last September! As I said, all of the plugs looked fine when I pulled them last week except #8 which was covered in carbon (not oil or gas), so I just assumed everything was alright, cleaned them and put them back in. Then again, it is a daily driver. With the way it was acting though, I could have sworn that it was electrical/computer timing related. The new TPS still needs adjusting, but it ran so good tonight. It almost feels wrong for it to be working right after more than a month of this stuff. I feel as if I've led everybody on a wild goose chase with all this stuff. Thanks to everyone who offered help on this one, esp. Vader and Mark (even though he didn't have anything to add ) for answering my desperate PMs and RSCamaroGuy92 for sticking with it right up to the end.

Thanks again guys,
Harry