My 90' Laser RS started acting funny after hitting fuel cut for the first time. It now idles and drives like it is missfiring. Occasionally idles and drives normal for a short period of time but then will start running rough again. The check engine light also comes on. I am trying to get a hold of a datalogger to see if that can help me out. I put in new colder plugs and still it runs rough.

any suggestions?

I would list out what you've done to the car so far (for mod's). That will help narrow down the problem.

Sounds like maybe an intercooler pipe blew off?

I have a boost controller, filter, up pipe, spark plug wires, and after all of this happened I put in colder plugs because I thaught maybe I had fouled out a plug or something. I was checking my boost gauge at idle and the vacuum is at 9-10 and that seems pretty low since when it runs fine it is at like 18-20. I was thinking maybe a vacuum leak.

I think you're right.

Do a boost leak test and listen for a hissing of some sort.

Yeah, it deffinately sounds like a blown off intercooler pipe, I would check all of those connections before you start hunting vacuum lines.

I checked all the pipes and they seem good. I don't know why the check engine light would come on though. There is a small hissing noise coming from around the injectors area. I had checked all the vacuum lines around that area and they are good. Do you think it could be like a intake manifold gasket or something of the sort?

The MAS might have come unplugged also, you might want to check that out.

Do a boost leak test. You are loosing vaccum pressure somewhere. Yes it could be an intake manifold gasket but it could also be several other things. You will find out when you do the boost leak test.

Would a car have less vaccum if the MAS was disconnected? The symptoms sound like he MAS unplugged but I dont see how that would affect vaccum pressure.

If the MAS is unplugged the car will not run properly. It will be overly rich and it will lose vacuum. Try it some time and see. :rolleyes:

I may try it with ghettostyle's car as mine doesn't run. The connector came unplugged from my MAS before but I didn't check the boost gauge. The car would not stop surging at idle and the cel was on. I scanned it with the datalogger and plugged the connector back in. It wasn't driven during the problem. Just started and shut off.

I helped her out and was playing around and put a new MAS in it and it seems to have solved the problem. The check engine light is now off and seems to boost fine. Thanks for all the info!

Well, the MAS seemed to work but it is running rough again and the check engine light continues to go on. I drove it to get something to eat and it ran fine, but when I came back out to start the car it started running rought again. Does anyone think there could be a short somewhere that could cause the MAS to go out? I'm going to try to get it scanned tomorrow, hopefully that will tell me something.
If you've got anymore ideas let me know. Thanks!

May be a loose wire on the MAS connector or something. Make sure it clips in because I have seen some shitty connectors on cars that dont always snap on. Does the car surge really bad at idle? That is what happened when my MAS became disconnected. It would surge very quickly up and down.

Alright, So it seems like we've tried everything. The MAS is good, the pipes are good, the cat was clogged so we cut that off, and the car is still running funny. Yesterday we started it up and it ran fine again, but as soon as we turned it off and then started it up again it ran rough. It doesn't make much sense, let me know if you guys can think of anything else. It really sucks that we can't figure out the problem.

Thanks.

Jet and someone else on here are having the same problem. Maybe they can chime in on this one. Check some of the other posts on other topics.

With the check engine light coming on, I would say that you want to check that before messing with anything else. You can do it with a voltmeter and a Chiltons.

Some days my beater runs better with it unplugged...then again, its a beater!

Yah I am trying to find a scanner or data logger; something that might be able to tell me whats wrong. We tried auto zone and checkers but no luck.
Can't find anyone who has one that will work with my car.
Anyone know where I can find one??