93 del sol, manual trans, ECU is 37820-P06-A01

was having intermittent non start traced to no fuel pump prime.
pulled ECU, found 2 bad caps (47 ufd cant tell number maybe C24, 33 ufd - C15)

cleaned up board, new caps


put ECU back in car, key on, check engine light goes out
fuel pump prime heard
car starts
happy days !

but

take it out for ride

2nd and 3rd gear, punch throttle, and have big miss between 2-3500 rpm.

no issues in first to 5500 with quick full throttle, and no issues on xway if i dont "punch" throttle but let speed run up slowly.


does ECU know the gear?
could this be ECU? it was not happening before pulling the ECU and replacing the caps.

thanks

 

Voltage test the TPS.
What engine?

Also:
Thread titles MUST summarize the tech problem so that members browsing titles can easily understand the problem without reading the post -- Title edited.

 

Sorry about the rules. I will try to do better.

1.5 Liter engine. most of the stuff underhood is gone. is that enuff info?

Heading to garage with voltmeter to find the TPS


but

until i replaced the caps, there was no issue with misfiring.

can you point me to connector diagram for ECU? perhaps I have a bad connector? But this does not happen in 1st gear.

 

http://www.phearable.net/tech/wiring...schematics.gif

 

Thx for diagram

interesting. TPM shows -0.5V at idle, -4.5 or so at full throttle. note the negative voltages. green wire is the same as chassis by continuity. perplexing, but checked it with 2 voltmeters. took care to make sure that black was in my COM connector and on the chassis. both times. did not check the yellow wire.

and, TPM has dead spot near full throttle. happens only when opening the throttle. and i cannot make the dead spot appear if i move the throttle real slowly. but if i move it quickly, and get near an open throttle, i get a transient 0.

but i am hesitant to replace the TPM, since this problem seems to have developed simultaneously with the repair to the ECU.


I cleaned the motherboard on the ECU to be sure no solder bridges (maybe was one, but i think that was wishful thinking). Careful driving shows that punching the throttle in 1st gear has same issue. Even if I stayed away from the place with the "dead spot."



and CEL comes on with key and goes off about the same time as fuel pump prime ends.

 

hard to believe that, despite over 40 years of doing this stuff, i had TWO different voltmeters hooked up backwards !

connector D pin 20 (sensor voltage for TPS) +5 v

connector D pin 11 (throttle position sensor) changes with throttle. quick movement above 3.5 V toward open throttle shows 1 dropout that cannot be reproduced with slowly opening throttle.

so my plan: take car for ride while monitoring pin 11 and see if voltage fluctuating while car is stumbling.

any chance you have schematic for ECU?

 

Nope -- If you find one, please let us know.

Are you using the D22 wire as ground for your voltage tests?

 

[QUOTE=RonJ@HT;47583458]Nope -- If you find one, please let us know.

Are you using the D22 wire as ground for your voltage tests?

QUOTE]



Was using chassis as ground both times [ underhood (punctured red wire underhood) or on pin D11]. I had previously pulled the TPS connector and checked green wire continuity to chassis - pretty much near 0 resistance and no issues with shaking the connector.

Good idea though. So on the ride I will have to look at TPS D11 ref to chassis as well as ref to D22.

Most sources indicate that the TPS issue most commonly occurs about 1/3 throttle. My dropout is pretty close to open throttle, and it happens only when opening throttle quickly.

 

well, this sure is fascinating.

pushed voltmeter pin into D11 on the ECU
took car for ride. had the babe drive so that i could watch VM for dropouts.

she couldnt make the car misbehave. i dumped her.
neither could i. so i went and got her back (its her car afterall).


could the ECU connector have been bad?
i could not bring myself to pull the ECU and recheck the pins. i had looked at all of those with 5x loupes and didnt see anything wrong.

so do the connectors go bad? i bet that i pulled this one off and put it back more than 12 times the repairs, reexaminations, etc. one would think that dirt would have been scraped off. i had tried to look at the connectors under the loupes but even with a powerful LED flashlight couldnt see much.

 

Well, if the problem does not return, then don't look back.

 

or under the kick panel.

as you probably know


The archenemy of good

is better.



Thanks for your help. I know where to look if the problem recurs.