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Old 03-04-2009, 07:05 AM   #1
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Default CAS, ECU, Coils??

My car is doing a few different things so I am having a hard time pinpointing the problem. It all started when I hit a bump and noticed the car skipped a beat. Only sometimes, I am loosing about 200-300 RPM's when I hit a good size bump. Secondly, sometimes the car just wont go. It will idol fine and then start to lag when I get out of the clutch. Once the clutch is all the way out it will just not pull at all. I can get it going again by letting off the throttle and then stabbing it several times. Also I am hearing some backfiring through the intake when its lagging. It seems to run better above 3 PSI. Other times it will run perfect. Overall the car seems to be getting slower and the problems are getting worse over time. I have searched and come up with three possible problems.

1. Leaking roof resulting in a damp ECU.
2. CAS is on the way out or loose wiring.
3. Coils either bad or loose wiring.

I have pretty much ruled out the first seeing how it has not really rained here in a while. As for the other two, I have checked the wiring and it looks fine. I am not throwing any cells and have checked up and down for vacume leaks. I have also tried replacing the afm with no results.
I would greatly appreciate any help fixing this because I want everything to be in perfect running order so I can get my MSPNP in and going. Thanks guys!!

Last edited by georgefury1; 03-04-2009 at 07:44 AM.
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Old 03-04-2009, 10:23 AM   #2
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Fuel filter?
bad AFM?

Both these had failed on me, and the sypathom could act from what you've discribed.
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Old 03-06-2009, 04:46 AM   #3
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Thats what I thought too. I already replaced it and the problems are still there.
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Old 03-07-2009, 09:21 AM   #4
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Update

My afr gauge stoped working. Could all this be a result of a bad o2 sensor?
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Old 03-07-2009, 12:26 PM   #5
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Quote:
Originally Posted by georgefury1 View Post
Update

My afr gauge stoped working. Could all this be a result of a bad o2 sensor?
It's very possible. Depends on how your engine management is using the oxygen sensor. Also, everyone thinks of fuel filter, but very few think of fuel pump. It took me a year to figure out my pump was bad (replaced almost everything else). It was strange, because it wouldn't fail all the time, but when it went bad, I had backfiring, lots of stumbling (unable to accelerate), and did it more when the car was cold.
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Old 03-07-2009, 12:56 PM   #6
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I don't know how 'cleanable' the AFM is because I'm not familiar enough with the 1.6, but try cleaning your AFM. There is a commercially available MAF spray cleaner, maybe this would work for the AFM. Dont rule out the possibility that the failing O2 sensor may be a symptom of the problem and not the cause.
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Old 03-07-2009, 01:02 PM   #7
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Sounds like a fueling issue to me. If the engine isn't stalling, you still have good spark. If you have replace the afm and filter the next step is the pump. You might want to stick a fuel pressure gauge on the rail. It sounds like the problem is intermittent, so the gauge might read the right pressure initially. Check it right when you start having trouble.

The failing O2 sensor is definitely not a cause. The stock ECU will just stop adjusting the mixture if the O2 sensor fails. I agree it could be a symptom though. O2 sensors fail from getting to much unburned gas in them or as a result off getting way to hot (running way too lean). Once again all roads lead to a fueling problem.
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Old 03-07-2009, 01:07 PM   #8
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Sounds like a fueling issue to me. If the engine isn't stalling, you still have good spark. If you have replace the afm and filter the next step is the pump. You might want to stick a fuel pressure gauge on the rail. It sounds like the problem is intermittent, so the gauge might read the right pressure initially. Check it right when you start having trouble.
The AFM is quite different from a MAF. The AFM is a mechanical measurement in a sealed compartment (picture a big copper disc with an arm like a record on it, the arm moves with the flapper door in the AFM). The only thing that could be cleaned is the air temp sensor, and probably just a blast of air would be fine for that.
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Old 03-07-2009, 01:08 PM   #9
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rofl ok man lets see i vote afm and vac leak somewhere. First make sure u have no vac leaks then investigate ur afm, even swap in a known good unit to coroborate if possible. A simple gauge on your fuel lines will show if it is the pump but i doubt it. The afm can cut ur pump off as well if it closes. Also verify u have some decent spark going on as well. If none of this works check ur timing and from there i would look into a clogged cat.
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Old 03-07-2009, 02:25 PM   #10
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When the O2 goes bad, its only going to tell the ECU to run rich by default, and most likely you will run in Open loop anyway so that's not the problem you had been having. If you want to know, just check your diagonsic box to see if its throwing you a code or two.
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Old 03-09-2009, 04:45 AM   #11
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Thanks for the feedback!! I will get a fuel gauge ASAP!! If I need a fuel pump, are all the Walbro 190 HPs the same. I have found a ton of them for the 94 n up but none for my year...92. Are they all the same or do I need to mod it to fit??

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Old 03-09-2009, 06:13 AM   #12
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The Walbro kit for 94+ will fit your 92. I've got mine form Lighteing Motorsport while its was the cheapest around that time, but that was like 2 years ago.
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