1990 4R Hard Starting

[rage2k10]

I have a 1990 Toyota 4 Runner. It idles rough, sprays too much fuel, and can't rev up. I installed new plugs, plug wires, and cap and rotors, even switched the computer mas airflow sensor and distributor from another working car (identical). Does anyone have a solution to this? Am I missing something? I also tried disconnecting the cold start injector.

I suspect that the TPS is malfunctioning?

Any ideas would be appreciated! THX!

 

[P.McKenna]

It could be a number of things: TPS, Vaccum Leak, EGR Stuck Open, Idle screw came loose on the TB. I could be one or a combination of these things things.

I assume its a 3VZE, so what are the RPMs running at when Cold & then at Normal Operating Temps ? Be more specific about the rough idle if you can.


BTW the TPS can be adjusted if it is out of adjustment. If in fact you are getting too much fuel the TPS could be telling the ECU your getting the proper amount when in reality its getting flooded do to it being out of Adjustment or just needs replacement.

 

[rage2k10]

Re

It could be a number of things: TPS, Vaccum Leak, EGR Stuck Open, Idle screw came loose on the TB. I could be one or a combination of these things things.

I assume its a 3VZE, so what are the RPMs running at when Cold & then at Normal Operating Temps ? Be more specific about the rough idle if you can.


BTW the TPS can be adjusted if it is out of adjustment. If in fact you are getting too much fuel the TPS could be telling the ECU your getting the proper amount when in reality its getting flooded do to it being out of Adjustment or just needs replacement.

Hi, thanks for the reply.

It is a 3VZE. When cold RPM is around 650, it's very hard to rev it up, even when it is at normal temp. EGR is eliminated. Vacuum only has 14psi at idle. I took out the TPS and checked the spec, it seems to be out of range. I'm cleaning up the throttle body and the intake manifold, and will try to set it up tomorrow. I will put a new O-ring on the idle screw as well.

If not I will open the timing cover to re-check the timing on the cam sprocket. A new timing belt was previously done. Also.. When it is at idle, I pulled the #1 #3 and #5 plug wires out one by one, it didn't make any difference on the RPM. It seems that there is no fuel in those cylinders, but it sparks at each wire.

This is what I've done so far.

Thanks again