90 laser idle/ throttle response issues

[Browniebrown]

I have a 90 laser fwd. I bought the car and it didn't run. I have replace a lot of parts. Nothing upgraded. I just need the car to run perfect before I begin on upgrades.it has a new fuel pump, fuel filter, new plugs new wires, new fuel tank, new fuel injectors, new ecu, new timing belt,I can't remember the rest so if you think you have a solution just ask and I will tell you if I put it in there. Basically the ecu just got here after the last one took a dump on me. The car was idling poorly before the ecu and the throttle response was also doing this. What it's doing is when I drive it it wil act Like its hitting fuel cut although I'm sure that's not what it is then once it's past about 3200 rpms it will act okay. In neutral when u rev on it it will barley do anything as if I'm not even pressing the gas. I've checked the timing on it twice and had a mechanic verify it was correct I just need some thoughts in what else it could be. Thanks. And sorry if I didnt explain it well it's hard to explain how poorly this car is running.

 

[acidreian]

check the compression on the cylinders and its possible if it has a maf that its clogged or dirty or just plan bad. if it was a different then stock map sensor could be the problem also.

 

[hondo0975]

There's lots of things it could be. If you have not done a boost leak check, do one if you can. If not atleast go over all vacuum lines an replace the ones that are dry wrought. One at a time. You could build your own boost test gage by just doing a Google search there are several with clear instructions on how to build one. Also go to VFAQ.com an look under intake, tps adjustment, it shows you how to adjust your tps. Its very easy. Mine had an issue where when the turbo would start to come on it felt like fuel cut an the problem wound up being a bad coil pack. Good luck. Hope I helped you.

 

[DSM1G90]

ECU is the MD 128625. If it's running that poorly, could almost be that the belt took a tooth or two jump - just to knock off valve timing but no interference problems.

 

[hondo0975]

Have you had any luck with figuring out what was wrong with your car?

 

[TurboLaserRS]

Have you installed the new ECU yet? What you're describing is almost to a TEE what mine did when I first got it running and it had a bad ECU. When I could manage to get it to a road and try to accelerate it would feel like it was hitting a rev limiter at 3000 RPM or so and it would spit and sputter and even backfire.
If you did replace the ECU, did you check the new one you got to make sure its not corroded or anything? I had to get 3 ecus before I found a good one and they all behaved similiar with blown capacitors.
You might also want to start it up in the dark and have a friend or family member watch under the hood while you try to rev it. I personally have bad luck with spark plug wires(Accels and MSDs will arc brand new out of the box) and sometimes they will idle ok but arc on the valve cover under certain loads / rpm ranges. That will feel like a very rapid rev limit as well.

 

[Browniebrown]

Thanks for all the replies. I think it's the MAF. I'll tell you why and if you think I'm wrong then I'll move on. When I was outside messing with it I unplugged the maf plug to clean off the connection. As soon as I unplugged it the car idles perfect. Like a brand new car. So I went for a ride around the block. The car rode so smooth just like it should. Plugged it back in just to make sure. Right away idle started acting up. Black smoke and backfire. Then drive it. Cuts out at 3200 rpms again. So is this just a matter of replacing the MAF or do you all think it's something else related. Thanks again. I'm getting close. Oh. Another question. I have to double clutch to put the car in gear. And with the clutch all the way to the floor rev up the car will move. I replaced the master cylinder. Litterally bleed it 5 times. Is it maybe the pedal needs adjusting or maybe slave cylinder. Thanks again everyone. And yes I looked the ecu over when I got it. I looks almost new. So I think it's good. Knock on wood.

 

[niddydsm]

Could be your engine coolant temp sensor. I just went through this and ect was the culprit

 

[Browniebrown]

Is the Ect expensive to change or is there a way to test it. I'm on an extremely tight budget. I've put a lot into this car so I would like to test it first. But I will look Into it. Do you not think its the Maf. Even though unplugging it makes it better. I've heard it goes into limp mode when it's unplugged.

 

[DSM1G90]

Thing about messing with sensors with power going through them (due to 5VDC coming from the ECU to the sensor when key is in the RUN position)is that they are in communication with the ECU. You break that connection link with power on and replug, it could destroy the drivers in the ECU, or at least blow a ground trace on the ECU.

Remember: the ECU is like a computer -dependable, but running DC current through the thing...and it doesn't like stuff coming off the momboard with the power still going through it - for it destroys the momboard.

Either way, it's an ECU rebuild. Trust me, I learned the hard way also. Thus, before I begin to mess with any ECU, sensors or similar, the negative cable comes off the battery immediately.

DSM

 

[hondo0975]

Here are a couple of threads that are similar to your issue. Google these...
1g gst runs good with maf unplugged
Car runs bad, unplug mass air meter, then runs fine-3000gt
Problem is it could still be many other things but these people in these two threads I mentioned above were having almost identical issues your explaining. An thank you DSM1G90 I did not know that I could mess up my ecu by unplugging sensors while negative was still hooked up or car running. I will log that information in my brain. Ill be the first to admit I still have lots to learn but it's fun...Browniebrown I hope you get your car up an running let us know.

 

[Browniebrown]

Thanks Hondo. You have been a big help. With anything like you said I am learning a lot with this car and with the knowledge of people on this site. And you can bet from now on I'll unplug my negative to. I can't afford to keep putting ecu's in this car. Thanks dsm1g90. I sure am glad you have a 90 laser . Something tells me I can learn a lot from you. Thanks everyone for everything. I will keep everyone posted. I hope to be driving a reliable stock laser within the month. I plan on zero upgrades until the car runs perfect for a year or so. But they are still fun stock. Lol.

 

[hondo0975]

Your welcome, glad to help.