Any ideas/it still misses/I have tried everything??

[Petersubaru]

86 MPFI Turbo..does anyone have any ideas as to why my car has a noticable miss at idle while in gear and not noticable at any other speed ...the car just passed the emissions test both at idle speed and at the 2500rpm test and passed with flying colors..I have checked the timing/idle is at 950 out of gear/new plugs and wires/new distributor cap/cleaned up the rotor/took starting fluid and sprayed the motor looking for vacuum leaks..I found one leak and corrected the problem, but still no change

[presslab]

86 MPFI Turbo..does anyone have any ideas as to why my car has a noticable miss at idle while in gear and not noticable at any other speed ...the car just passed the emissions test both at idle speed and at the 2500rpm test and passed with flying colors..I have checked the timing/idle is at 950 out of gear/new plugs and wires/new distributor cap/cleaned up the rotor/took starting fluid and sprayed the motor looking for vacuum leaks..I found one leak and corrected the problem, but still no change

 

Try some seafoam in the gas tank. It cleaned up my idle.

[Petersubaru]

I will put the seafoam in directly thru the Pvc or someother port...Thanks

Try some seafoam in the gas tank. It cleaned up my idle.

[Subi81]

I have a similar problem. I have checked and changed lots of stuff;

You might want to check your thermovacuum valve. I have found mine to be defective and everyone that I got from the junkyard too.

Here is a pic of what it looks like

 

 

here's how to test,

plug the port closest to the brass part of valve

blow air into either other port

air should pass if valve is below 113 deg F

air should NOT pass if valve is above 131 deg F

 

Remove plug then plug port on the end opposite the brass part

blow air into either other port

air should pass if valve is above 68 deg F

air should NOT pass if valve is below 50 deg F

 

cap

vacuum advance mine was broken, had it rebuilt by:

http://www.philbingroup.com/rebuilt/special_services.htm

Ours is the Vacuum advance-single $25.00

rotor

wire

plugs

fuel filter

checked fuel pressure

air flow meter

computer

timing

distribultor

temp sensor

timing belts

looked for vacuum leaks

 

And I still haven't found the problem.

 

My car misses so bad that I failed my emmisions test at the 2500 range. At idle I was within spec though, but I feel your pain about misfires. I am about to give up and take it to subaru and let them figure it out, with thei fancy dancy machines, tell me what is wrong and let me fix it.

 

I just found this site that I think might make you feel better:

http://www.parttrackers.com/library/1/117/122/

 

"On '85 and '86 turbos, the computer is a little lean, and you get surging problems. What we do is retard the ignition timing two degrees, which eliminates the action of the knock sensor. It helps. Putting resistance in the coolant temperature wire makes very little difference, not like on a Z-Car, for instance."

 

Sorry if this is not much help. But know that there are other people out there with the same problem.

 

So where was your one vac leak that you fixed?

 

Good luck,

While researching this problem I have found that finding a misfire is one of the hardest things to track down.

[Petersubaru]

I seem to be a little more fortunate then you since my Sub has just passed the emmission tests with near new specs for a car that has 200,000miles...the vacuum leak(a long crack) I mentioned earlier was under the big rubber pipe coming from the maf to the throttle body..I would have never seen it, but the use of propane and wd40 sniffed it out...I have done mostly what is on your list and I suspect that maybe one of the injectors is not working as should...I am thinking in this direction because as long as the motor is warming up, there is no miss....the miss, is only at idle and not necessarily all the time , sometimes the missing can be weak or stronger...I noticed on your long list that no mention of an EGR..if you have checked for leaks and vacuum, did you check that the manifold side is not plugged up ...also no mention of an O2 sensor which is more important on the emmission side of things then smooth running....I have gut feeling that when you get your car up to pass the emmi., you will still have the Miss...Good Luck

I have a similar problem. I have checked and changed lots of stuff;

You might want to check your thermovacuum valve. I have found mine to be defective and everyone that I got from the junkyard too.

Here is a pic of what it looks like

 

 

here's how to test,

plug the port closest to the brass part of valve

blow air into either other port

air should pass if valve is below 113 deg F

air should NOT pass if valve is above 131 deg F

 

Remove plug then plug port on the end opposite the brass part

blow air into either other port

air should pass if valve is above 68 deg F

air should NOT pass if valve is below 50 deg F

 

cap

vacuum advance mine was broken, had it rebuilt by:

http://www.philbingroup.com/rebuilt/special_services.htm

Ours is the Vacuum advance-single $25.00

rotor

wire

plugs

fuel filter

checked fuel pressure

air flow meter

computer

timing

distribultor

temp sensor

timing belts

looked for vacuum leaks

 

And I still haven't found the problem.

 

My car misses so bad that I failed my emmisions test at the 2500 range. At idle I was within spec though, but I feel your pain about misfires. I am about to give up and take it to subaru and let them figure it out, with thei fancy dancy machines, tell me what is wrong and let me fix it.

 

I just found this site that I think might make you feel better:

http://www.parttrackers.com/library/1/117/122/

 

"On '85 and '86 turbos, the computer is a little lean, and you get surging problems. What we do is retard the ignition timing two degrees, which eliminates the action of the knock sensor. It helps. Putting resistance in the coolant temperature wire makes very little difference, not like on a Z-Car, for instance."

 

Sorry if this is not much help. But know that there are other people out there with the same problem.

 

So where was your one vac leak that you fixed?

 

Good luck,

While researching this problem I have found that finding a misfire is one of the hardest things to track down.

[Subi81]

Sorry yea I replaced my O2 sensor with little effect.

 

Took off tested and cleaned my EGR but didn't check the tube going to the exhaust pipe, for flow.

 

Guess I will have to check out my intake boot.

 

I have to agree with you I think the miss is here to stay.

[Petersubaru]

I forgot to ask, when checking your computor(ECU), did you just look for codes to come up or did you actually exchange the ECU???...years ago I had an ECU that caused the car to misfire...today I started the car up and the "miss" went from idle thru the whole rpm range...seems like my problem has only increased and maybe it will be easier for the mechanic to find the problem..I am interested to what you have to say concerning the ECU...maybe I will swap mine out and see what happens...after all, the only 2 things that have not been checked or replaced, is the ECU and injector(s)...the previous owner according to the worksheet at the garage had the whole injection system cleaned about 30,000mi. ago....

Sorry yea I replaced my O2 sensor with little effect.

 

Took off tested and cleaned my EGR but didn't check the tube going to the exhaust pipe, for flow.

 

Guess I will have to check out my intake boot.

 

I have to agree with you I think the miss is here to stay.