I just got my car to run again after 2 months of being broken. Replaced timing chain and gears water pump distributor ignition coil plugs wires fuel pump fuel filter Throttle Position Sensor. It now idles at 1500 rpm pretty steady. I have been trying to figure it out for a few days now. Sprayed Carb cleaner all around the intake I did find 2 vacuum leaks and repaired them. it got better was erratic now its steady 1500rpm. I have been trying to put the new TPS on it but cant get the .5 volts the book call for. I dont have any voltage running to the TPS wires at all. If i unplug the MAF sensor the idle drops to 500 and it sounds good but the car wont drive as soon as i push the gas it dies. I tried putting the jumper wire in to check for codes but the service engine light doesnt come on at all. I am thinking my ECM is bad but dont want to spend the money on it and not be the problem.

 

Have you tried tapping your idle air control valve gently with a spanner or a screwdriver handle and seeing if the idle changes, sometimes they get gummed up or they fail.

Matthew

Edit: just seen the bit about the TPS... it could be your ECM or it could be a fault in the wiring to the TPS?

 

If the TPS has been replaced, it's probably not putting out a low enough signal for the ECM to realize the throttle plate is closed and an idle condition is desired. Between the blue and black wires on the TPS, a voltmeter should read around .55 VDC, not much higher than that (.6V).

:edit: You obviously have an 88+ car (year helps a lot), and the TPS is non adjustable (supposedly). Get a Dremel or a drill and widen the screw holes into slots. Then adjust the TPS.

The gray wire at the TPS should see around 5V with the key on... the others won't have a reading because the black wire is ground and the blue wire's voltage is regulated by the internal resistance of the TPS.

 

i have an 89 and the tps is adjustable i tried that first. I dont need a dremmel because the holes already come slotted. I replaced the ecm and now i am getting voltage to the tps. I can unplug the MAF sensor and it will idle perfectly. but as soon as i plug it back in the idle jumps to 200rpm. I have replaced the TPS, MAF, Idle Air Control Sensor, EGR Valve, Intake Manifold Gaskets, Checked for leaks found a few repaired them with no change, Replaced The ECM but still can not get the idle to drop below 2000 rmp unless the MAF is disconnected but with it disconnected as soon as i push the gas pedal the car dies.

 

Maverick H1L is right about Get a Dremel or a drill and widen the screw holes into slots. Then adjust the TPS., The reason why I agree with him on this is because yes your right they already have a hole but at times you have to widen it or move the hole at an angle to get the correct adjustment. A friend of mine did that to my TPS and now I'm getting a perfect idle....

What is your reading on your TPS? Where you able to get one yet?

 

Check and adjust the TPS before you go diving into the MAF, which is an expensive little bugger (that I also need to replace). Once the TPS is set, then you can find out what is wrong with the MAF.

Remove the MAF, and look at the orange/gold film inside. It should be as flat as the mirror in your bathroom (and reflect light the same). If the light you shine through the inlet end doesn't appear the same all the way across the film, you need a new sensor. That's the only way to check it without either a scanner or a multimeter that reads frequency.

BTW, I appreciate the support for the TPS "fix" on the later models. It's too bad others don't support it as well.

 

Maverick H1L your famous for saying .....

Remove the MAF, and look at the orange/gold film inside. It should be as flat as the mirror in your bathroom (and reflect light the same). If the light you shine through the inlet end doesn't appear the same all the way across the film, you need a new sensor.

.... I know you told me the same thing but I'm just curious and hopfully you can help me and others that would like to see what I'm going to ask...what are the odds of taken a pix of what your talking about, MAF and that orange gold film....Please?

Thanks man in advance....

 

Yours doesn't have one, plain and simple. If you did, it would be a round tube with a rectangular box attached with a 3-wire connector on the left side. Your car has a speed density system with a Manifold Absolute Pressure/Barometric Pressure (vacuum) sensor. It will be bolted to a bracket above and just to the right of the A/C evaporator case, between it and the distributor.

:edit: That's a good idea though, I'll have to add that (sensors and other parts pics) to the repair guide I'm writing (that I've been slacking on lately and haven't touched in over 2 weeks ).

 

Thanks man....and heard about what your putting together, Very sweet for dudes like me. As for pictures that would be the key for the visual understanding that some of us need. Cant wait till you finish it man and hope it turns out good.

P.S. How do I check to see if the MAP sensor is still good?

 

Yep... Page 11 and I haven't even hardly started yet. Of course it's in 12pt so it can be read easily from a bit of a distance away.

Anyways, you'll need to find the voltage reading between the light green wire and the black wire coming from the MAP. The gray wire won't help you as it's a 5V reference signal coming from the ECM. However, you'll want to check to make sure that the reference wire has a signal near 5V.

 

found a group of wires on the passenger side of the waterpump had 7 wires in it that were pretty tore up so i cut and spliced them back to gether and it worked like a champ one was the blue wire running to the tps thats how i found it. was almost broke in half. took it out on a drive last night runs better than it ever has. thanks for the help if you guys hadnt stressed the tps so much i would never have found it.