Dyno Day results: "Your car has big problems"... HELP

[WA2FAST]

Compression testing came out fine. I have 150-160 across the board. Obviously that is not my problem... I didn't think so, but it is good piece of mind and I wouldn't feel "dumb" later down the road if I never did one, then finaly decided to do one and had half a blown motor ;) Anyway, I fired the car up yesterday when I was done compression testing and I kind of have a better idea as to what is happening... I just need to find out why now. I know that my a/f gauge is no true test to a/f ratio, but in this case, it is saying something, that is for sure. I have the gauge probed into the drivers side O2 wire. Once sensor warms up, the gauge starts dancing around and so on. If I hold the RPM's up around3-4k (which is VERY light throttle pressure), it will hold just fine, then about 4-5 seconds later, the a/f gauge drops off of the lean end FAST, and the rpms fall (obviously) and it will sit there caughing and sputtering till I take my foot off, then it immediately goes back to normal, a/f gauge starts dancing around again... it is a little sluggish and towards the lean end for a few seconds (almost like it is trying to catch back up) but then the car is fine. It never hunts for idle, it never stalls, nothing... it just INSTANTLY goes super lean, totaly like a fuel cut, and when I let off... it goes back to normal right away. This seems to be a load issue because at idle, I can rev it quite a bit before it does this, but when trying to actually drive the car, it falls on it's face right from a start bassicaly. Has anyone heard of this before? I checked the TPS voltage and it seems linear, no blips or anything. A few people are still pointing fingers at the meter, but why did my car do the same thing with Anthony's on it then? Any ideas? I feel like a dog chasing it's tail in circles.

[SnakeIs]

I think its in your EEC, I had similar problems and they still existed even when I forked up the cash and bought a Univer. I ended up playing with the wideband in my car for a few days and used my eec tuner to cut off closed loop operation and the problem went away instantly! To this day my car will not run in CL with the blower. It doesn't run any worse in open loop and is actually easier to tune cause I'm not fighting the EEC trying to tune "around" me. It is so much easier to tune in open loop. I'm not sure who is tuning your car, but get them to lock it in OL and see what it does...

[WA2FAST]

Well, my car was run in open loop with the N/A setup I had for years, but I don't know if that is the answer. In Open Loop, it still needs the MAF transfer function, and if that is out of whack (which mine is) then it's not going to be right. I think that my car is ready to hit the dyno again, so we'll see what Don Walsh says when I call him up. I feel half confident at least that I may get a working car back this time.

[SnakeIs]

I'd almost bet that Don (or any good tuner) can get that problem fixed. So does Don tune in open loop or closed? what type of chip is he using? Autologic, Superchips? I am curious as to what the real tuners do with blown cars because in closed loop the EEC will constantly be trying to correct your Air/Fuel to a set value in the tables but in open loop you have full control over what tables and values it uses with no corrections and with a blower you naturally run much richer than what the factory intended.

[WA2FAST]

He tunes most of the time in Open Loop as Closed Loop is very seldomly used to my understanding unless it is absolutely needed. He uses Autologic chips. As far as tuning a blown car in open loop, I was always under the impression that it was a very bad idea to do so because the ambient temps, air temps, and so on change so much. I could see a nice open loop tune that just dumps fuel, but that can hardly be efficient in making power considering the fact that you would have to compinsate for when the air was less dense and hotter so that in those conditions you don't blow the motor, but I could be wrong. When I originally spoke with him about my car, even though my car had been tuned in open loop with my N/A setup (I have never been happier with a tune... that was the best tune ever, being in OL definitly helped it too cause it was consistant), he wanted me to put in new O2's and make sure that they were working properly cause that is crutial. He made it sound like he would never tune a blown car in OL, but again, he never said that, just going off of how he acted when I asked about the O2's.

[SnakeIs]

Thats what I was always told, because even with the wide band and my tuner I cannot get consistent tunes with Closed loop, the EEC always ends up tuning out what changes I make with adaptive strategy. Once I figured out how to lock my EEC in OL my tuning got so easy, all I did was watch the wideband and set the fuel tables to where I wanted it. It stays dead on now and makes great power, with just a slight drop in MPG. Since my blower let go I have bypassed it and have been running the car N/A with the big injectors and the Univer and I actually have it running great in closed loop now, so I may just TRY closed loop when the blower goes back on but it probably wont work..

[WA2FAST]

Hmm, I wonder why it makes a difference between having the blower hooked up or not... as far as drivability is concerned (out of boost), your car should run exactly the same with or without the blower. If it is running okay now without the blower attached, I have a feeling that you will be able to tune it in CL.

[SnakeIs]

Well, not actually because when in boost I want the car really safe with a max of 12.0AFR and the factory has it a little leaner than I like especially with the Univer. It always seemed to buck at part throttle with the blower and in closed loop but that goes away as soon as I force open loop. I'm sure a GOOD tuner could probably fix that with the MAF curve but I haven't gotten that good yet...

[WA2FAST]

Yea, I hear you.... well with my car, just for an update, I had O2 harness problems, big time. After fixing those problems, my a/f gauge finally reads really well and the car seems to be acting like a normal car (compensating using the O2's). Without the meter plugged in, the car runs just fine now, no problems what so ever (obviously not in boost). With the meter plugged in, the a/f gauge falls off of the lean end after about 3 seconds of part throttle and heavy vacuum (20-23), (especially under normal operating temp) and misses like crazy, in fact, it doesn't miss, it's like a flat out fuel cut basically... its almost like someone cut the bat cable till you let off of the gas, then it comes right back to life where it should be, never stalls afterwards. With the meter un-plugged, you can see it do the same exact thing on the gauge (go to the lean end quickly), but it doesn't fall off, and that's when it starts fluctuating to regulate it's a/f... so there are no problems. So what I get out of that, is that the meter is making the car run so damn lean, that when it goes to make that compensation, it goes too far because the meter is off... otherwise it wouldn't go that far lean (just like how it does it without the meter plugged in). Those things compiled with the fact that I have long tubes is just spelling out L.E.A.N. all over the place. Long tubes move the O2 sensor so far away from the combustion chamber, that the car has to run lean in order to heat it up to the correct range, hence it is getting a false reading... which is why any car with long tubes should be tuned no matter what. Anyway, the car seems to be running a ton better since I fixed my few harness problems, so we'll see what happens on the dyno once I can get a hold of Walsh.

[SnakeIs]

Cool, sounds like your getting to the bottom of it finally. But as an FYI- When you run longtubes the 02's are kept cold and don't heat up as fast therfore the EEC ENRICHENS the fuel because it thinks the motor is colder than what it really is. At least that is what I have been told by some very reputable tuners. I am getting ready to go with 1 3/4" longtubes myself and cant wait to see what it does to my tune... back on with the wide band!

[WA2FAST]

Nope, that's backwards... rich a/f results in cooler exhaust temps, lean conditions result in hotter exhaust temps. The thing is, is that the EEC thinks that it is doing the right thing, it's just that the O2's have been moved from their original place, so the heat range for them is going to be different... that's why anyone with longtubes should have their car tuned... they aren't going to get any of the added benefits of them if the computer is screwing up the a/f ratio.

[WA2FAST]

Okay, so after a long and involved process of troubleshooting and fixing things, I have fixed wiring harnesses, I had my upper intake machined to get rid of the warps on the base plate so that it wouldn't leak anymore, I sent the meter back to Pro-M, they supposidly fixed it, re-adjusted my rocker arms, and here I am now with a car that still isn't working right.

I think I see now what is happening. I was monitoring the meter's voltage very closely yesterday after starting it up for the first time with EVERYTHING done (intake and all) and the voltage range was amazingly at .600-.700 at idle! That was a nice suprise... the car seemed to be running great, no problems at all. I noticed as time went on and the car started warming up, the meter's voltage started dropping lower and lower gradually. Finally by the the time I got to normal operating temp (180), the meter's voltage was right back down to .200-.300 where it was before... car was running terribly lean, eyes were burning and all.

Obviously the meter is the problem, but the question is WHAT is making it go out of range? What exactly is making it lose it's refrence? The ONLY thing I can think of is heat. The only thing that changes on that car as it warms up is the fact that it is warming up. It seems like this meter is GREATLY affected by heat. I took the meter off of the car for about 5 minutes to let it cool off, plugged it back in and the voltage was right around .400-.500 for a short while before it dropped again.

My question is this. I am pretty sure about this, but the meter's voltage is NOT adjusted by any other sensor on the car right? What I mean is that the coolant temp sensor doesn't affect the voltage that the computer sees from the meter right? I am 99% sure that all of the sensors talk to the computer individually and the computer makes it's decision based on that, the voltages from sensor to sensor have nothing to do with eachother.

Any input? I am running out of time fast here. My patients are gone too... so any help is greatly appreciated. Thanx guys.

[SnakeIs]

There is nothing else that affects MAF voltage. It sounds to me like the board in the Meter is getting hot and when transistors and resistors get hot, their resistance values change which would cause your varying voltage. Is there anyway you can cover the MAF with something to sheild it from heat? maybe header wrap or and aluminum shroud of soem type.... if that doesn't do it then I'd demand Pro M to replace your meter.

[WA2FAST]

Pro-M's outstanding customer service provails as they NEVER called me back yesterday and I now have to wait for them to answer the phones so that I can try again today. Does anyone have any suggestions or ideas as to why my meter is reading different once the car is running?

[WA2FAST]

Okay, so I finaly got ahold of Pro-M and the guy that I talked to bassicaly said "well if the meter is running fine when the car is cold then there is nothing wrong with it. If you try un-plugging the O2's see if that cures it. Short of that I can't help you unless you bring the car in. I will have Jim call you back." Unless there is another sensor on my car that directly affects the voltage being sent from the meter to the computer, it IS the meter or design of the meter that is bad since it doesn't work right once the car starts warming up. I told him the O2's have nothing to do with it because it's the meter's voltage that is going down when the car is running not the O2's.

What do I do!!!??? I am so tired of this! I can't stand it anymore!