1G Won't run right

[americanrice]

Why does my 1990 laser RS turbo have an off idle miss and not rev past 3000 rpm.

 

[steve]

Cause it's old and busted?

 

[americanrice]

Cause it's old and busted?

Yes it is but I want to change that. Can you help me out? When I give it throttle it cuts out and won't rev past 3000 rpm.

do you have any thing to say that might be some help to me.

 

[steve]

If you read around you'll see I have much to say but you haven't given anyone much to work with.

So lets start with the basics, has your ECU had it's capacitors changed?
What was the last time you did the spark plug wires and plugs? Fuel and Air filters?
What's your compression like.

What's the electrical system voltage when It's acting up? It will run like crap if the alternator isn't working and the battery voltage drops.

 

[pauleyman]

You need to provide more information. That's what we're saying. What have you done? Is this a new development? What's done to the car? Fill out a profile. We dont have crystal balls.

 

[steve]

We don't have crystal balls.

I did but it's long since run dry of blinker fluid. Now I have to depend on my Magic 8-Ball.

 

[americanrice]

If you read around you'll see I have much to say but you haven't given anyone much to work with.

So lets start with the basics, has your ECU had it's capacitors changed?
What was the last time you did the spark plug wires and plugs? Fuel and Air filters?
What's your compression like.

Ok thank you Steve. The car has sat for 10 years and I bought it for a project. It has a new stock turbo, head gasket, reman mass airflow sensor, 190 lph pump, and adjustable fpr.

It has not had it's capacitors changed, it has new ngk plugs, the plug wires passed a resistance test I have not changed the fuel filter or done an compression check.

 

[pauleyman]

Yes it is but I want to change that.can you help me out.when I give it throttle it cuts out and won't rev past 3000 rpm

Ok thank you Steve.the car has sat for 10 years and I bought it for a project.it has a new stock turbo, head gasket,reman mass airflow sensor,190 lph pump,adjustable fpr.It has not had it's capacitors changed,it has new ngk plugs,the plug wires passed a resistance test I have not changed the fuel filter or done an compression check.

I would start with checking mechanical timing, ignition timing and compression or even better leakdown.
Take a visual of the ecu also. See of there is anything obvious. Leaking, trace damage etc.

 

[steve]

'90s are special like so many first model year cars. They fixed a whole bunch of things with the 91's.
It's critical to get the ECU looked after ASAP, unlike the later cars the capacitors in the 90 ECUs have a nasty tendency to dry out and catch fire. You'll want to have them replaced before they do that.

Paul's right. Next thing on the list with a project car like this one is checking mechanical timing, if you don't know when the belt, pulleys, and tensioner was changed you should replace them so you're not playing with a time bomb.

Closely look at all the wiring in the engine bay. After years of heat cycling the insulation gets cracked and broken. There are many problem areas but two common places to look out for is the Engine Coolant Temp Sensor wiring and the Idle Position Switch wiring.

All this stuff should keep you busy for a day or two.

 

[americanrice]

I would start with checking mechanical timing, ignition timing and compression or even better leakdown.
Take a visual of the ecu also. See of there is anything obvious. Leaking, trace damage

I have not changed the fuel filter or done an compression check

 

[americanrice]

'90s are special like so many first model year cars. They fixed a whole bunch of things with the 91's.
It's critical to get the ECU looked after ASAP, unlike the later cars the capacitors in the 90 ECUs have a nasty tendency to dry out and catch fire. You'll want to have them replaced before they do that.

Paul's right. Next thing on the list with a project car like this one is checking mechanical timing, if you don't know when the belt, pulleys, and tensioner was changed you should replace them so you're not playing with a time bomb.

Closely look at all the wiring in the engine bay. After years of heat cycling the insulation gets cracked and broken. There are many problem areas but two common places to look out for is the Engine Coolant Temp Sensor wiring and the Idle Position Switch wiring.

All this stuff should keep you busy for a day or two.

Thanks for the input here.kind of have one thing to tell you.The engine idles with a slight miss.when I give it throttle it immediately begins to act like the injectors or coils are being cycled of and on.all four cylinders will be affected by this and engine will still rev up to but not beyond 3000 rpms.

 

[steve]

kind of have one thing to tell you.The engine idles with a slight miss.when I give it throttle it immediately begins to act like the injectors or coils are being cycled of and on.all four cylinders will be affected by this and engine will still rev up to but not beyond 3000 rpms.

I got that from your first post.

How bad is the miss? It's not uncommon for them to have a random occasional miss at idle. I wish mine purred but it spits every couple of seconds when idling. It's also old and occasionally broken.

Sadly, there are many reasons why it might not want to rev pas 3k. Which is why you now have a list of things to look into and report back on before the diagnosis can go much farther.

 

[americanrice]

Thanks for the input here.kind of have one thing to tell you.The engine idles with a slight miss.when I give it throttle it immediately begins to act like the injectors or coils are being cycled of and on.all four cylinders will be affected by this and engine will still rev up to but not beyond 3000 rpms.

I got that from your first post.

How bad is the miss? It's not uncommon for them to have a random occasional miss at idle. I wish mine purred but it spits every couple of seconds when idling. It's also old and occasionally broken.

Sadly, there are many reasons why it might not want to rev pas 3k. Which is why you now have a list of things to look into and report back on before the diagnosis can go much farther.

Ok Steve thank you for your help.I will do some more looking as you said.

 

[Dericsh]

Follow the DSM maintenance guide. This thread has links for how to do a boost leak test and compression test if you need help with that.

Use this Ecm inspection wiki to check for common issues on your ecm. If you find any issues I would recommend sending your ecm off to ecmtuning for repair.

 

[Vegas Smith]

I recall that the fuel filters get clogged after so many years sitting and make sure you have fresh gasoline.