Chasing a ghost, need help bad!!!

[dgreen1069]

What happens when a crank sensor malfunctions? What are the symptoms?

How much retard is normal at wot at the 1-2 shift on a stock car? What causes excessive retard on a stock car? I saw 10 on my scanmaster this afternoon while I was checking all my readings. That was at WOT just after the 1-2 shift. The O2s were around 810 (on pump gas).

I have a slight miss that is most noticeable at cruising speeds when the TC is locked. I have a scanmaster and everything seems to be where it should be. I have pulled my plugs and they look fine. I thought my injectors might be the problem, but now I don't know....I thought I would see something with the plugs. My car only has 6,000 miles and is bone stock. This problem is driving me nuts....it is like chasing a ghost. Would a bad coil pack cause a miss or slightly rough idle? Is there any way to find the problem without replacing parts one at a time? Anyone near No. Va that knows these cars? Please help before I go nuts!

 

[dgreen1069]

I forgot to add that the plugs have been replaced and the wires were swapped (temporarily) with new ones. The intake was also cleaned out thoroughly. Neither the plugs or the wires improved the slight miss.

 

[turbot2496]

If the problem started out of the blue, I would suspect you may have gotten a bad tank of gas. If possible you could put some race gas in and see if that clears the retard up or drain the tank through the fuel rail and try some new high octane fuel. Bad gas will cause alot of weird problems. I would start here.

 

[dgreen1069]

I purchased the car with 4,700 miles on it. I have been having this problem since I bought the car. The miss is minor (feels like a big cam), but is noticeable when the TC is locked and the car is cruising. The original sending unit rotted while the car was in storage, so the original owner had a new tank/sending unit installed. The fuel filter was also replaced at that time, along with every other fluid and the plugs. I have since replaced the plugs again and put in mobil 1 oil.

 

[turbot2496]

Got a little time so I'll try to go through these one by one

What happens when a crank sensor malfunctions? What are the symptoms?

Usually car won't run at all. I doubt this is your problem

How much retard is normal at wot at the 1-2 shift on a stock car?

Well zero on my car but under 2 degrees should be ok as long as it goes away after the shift

What causes excessive retard on a stock car?

Too much boost, too little octane, too little fuel, or too much timing are the main causes. Also something banging around can set off the knock sensor and cause retard

Would a bad coil pack cause a miss or slightly rough idle?

Its possible. I would swap with someone who has a known good one or use a tester if possible

Is there any way to find the problem without replacing parts one at a time?

My best advice since you are new to these cars is to find someone near you you can swap parts with and track this down.


Start another post with subject "Anyone near No. Va that knows these cars?" and see if theres anybody close to give you a hand.

And don't go nuts. Sounds like the car has been sitting a long time but I doubt its anything serious.

What chip are you running? Also how much boost?

 

[darkred87T]

Did you find the problem? if not, you're not alone. Where are your MAF counts? BLM's? I have the same problem with my car and Iv'e replaced EVERYTHING and I have a rebuilt motor. The car misses the second I start it cold and when it finally goes to closed loop, the idle is rough and weak with an off-idle hesitation. It often throws 42 codes (Low MAF) because MAF is usually around 4. BLM's are high at idle. It looks like a circus under the hood when it idles, the engine rocks and shakes all over the place. However, it does smooth out during cruising conditions. Didn't mean to jack your thread but I feel your pain. Good luck and let me know if you fiqure it out or if you have any questions.

 

[dgreen1069]

I have not fixed my problem yet. I will post again when I find out what my BLMs are at idle. What should they be? I will find out what all my Scanmaster readings are at idle so you guys can continue helping me diagnose things.

What you described with your idle is almost exactly what I am seeing. I think whatever I find in the end is going to be simple. Other than being 18 years old, all of my car's parts are practically new.

I am running high test gas (93 octane) with the factory chip.

 

[darkred87T]

I'm currently running a 98 extender chip with a program idle of about 950 RPM. The higher idle seems to help a little. BLM's should 128-135 at idle and MAF should be about 6. Check out www.gnttype.org and you can find out what your #'s shoul dlook like at idle.

 

[dgreen1069]

Darkred87T, did you ever find your problem? I don't know if I am describing my problem well enough for people to help me. Basically, my car starts up just fine and idles ok. The idle seems to be rougher than it should be. The engine does not miss, pop, or backfire.....it just runs a little rough. When cruising down the street, there is a very mild bucking that feels like a small miss when the TC is locked. It might be doing it the whole time, but it is more noticeable when the TC is locked.

I have used the search feature and have found several threads with complaints similar to mine, but nobody has posted the exact fix. A few people hinted around that the problem may be the MAF. Could the MAF cause these symptoms? I have cleaned the intake, replaced the plugs, checked the wires (and tried replacements), and rechecked the plugs (thinking that maybe I had a bad injector).

Here are my readings at idle:

ATS:80
BL: 130
INT: 125-135
AF: 06
L8: 50

The car seems to run fine at WOT, but I am getting a bit of retard. I got a retard of 7 at 54mph. The O2's hit 812 at 15mph (I think..if the direct scan is showing the 02's mph in the left display).

 

[turbo2nr]

Those numbers look good. How about TPS at idle. Also IAC. Have you checked all vacume hoses? Anybody messed around with anything under the hood?

 

[darkred87T]

I'm confused. When you said your AF is 6, were your referring to MAF? If so that's a perfect MAF count at idle.

 

[dgreen1069]

I am fairly new to the DirectScan, but I think the AF is for MAF. My TPS is set to .44 and the IAC is always between 20-35 (it is steady, but it is never exactly the same).

 

[darkred87T]

On the Direct Scan, it says MAF and it's right over "IAC" and under "LV8". And again, 6 is a good number for MAF. "A/F" is air/fuel ratio and is located in the center of the screen above the BLM chart. This count should be around 14:1 at idle, (I think). If your IAC counts are 25-30, that is normal and proabably means you don't have a vacume leak. If you did the ECM would shut the IAC valve completely to compensate resulting in a "0" for IAC.

 

[darkred87T]

Oops, I just realized you are using Scanmaster. Abbreviations may be different than Dorect Scan which is what I use.