Diagnostic Game

[AcuraTech]

Alright I think we've had enough replies for this. All I can say is that nobody has guessed it yet! I forgot to say in the initial diagnosis that when idling in park the throttle response was also poor.

Anyway, the problem turned out to be the TPS sensor! Key on engine off I was getting a little over 2V with the throttle fully closed from the TPS signal output. With throttle closed the signal should have been around .5V.

So the engine thought the throttle was partially open and was dumping fuel accordingly. But the throttle plate was fully closed so it was running rich, hence the smoke and fuel smell from the tailpipe.

So I replaced the TPS with a new DELPHI unit and it was good to go!

 

[wavinwayne]

I fought an issue with similar symptoms on a '94 Chevy Beretta years ago. I also replaced the TPS sensor, hoping that was my problem. It wasn't. I finally gave up and took it to a mechanic. It was the knock sensor. I had that replaced and it fixed the problem. I suspect that car also had a LIM gasket and/or head gasket leak. I gave it to my sister with approx. 150k miles on it. She drove it for a couple more years, then something finally killed it. I didn't ask what it was.

 

[brianl703]

I once had a problem with my old car where it would continue revving the engine when you pushed the clutch pedal and slowly come back to idle.

I replaced the TPS and that was the end of that problem.

Fords will throw a code if the TPS reading doesn't correspond with the MAF reading.

 

[punisher]

Originally Posted By: brianl703
I once had a problem with my old car where it would continue revving the engine when you pushed the clutch pedal and slowly come back to idle.

I replaced the TPS and that was the end of that problem.

Fords will throw a code if the TPS reading doesn't correspond with the MAF reading.


Sometimes it will. We had a lot of those TPS problems on the Contour/Mystiques for awhile.

 

[The_Jeff]

Crazy, there you go.

With these smog rules the biggest thing the TPS seems to do in my cars is activate the "dashpot" Idle speed controller wide open. Any accellerator position above zero makes the ISC open wide. Also makes the car feel peppier just off idle, I am sure not an accident on their part.

My saturns recalibrate TPS zero every start, so "rebooting" a high idle and having it settle indicts the TPS in this instance. Also no code b/c it's a theoretically possible voltage.

 

[brianl703]

Originally Posted By: eljefino

My saturns recalibrate TPS zero every start


I think the Fox-body Mustangs do this as well, despite all the stuff about "calibrating" the TPS to exactly 0.98V idle (or whatever the voltage is).

 

[Audi Junkie]

Vacuum leak?

 

[Nyquist]

Originally Posted By: AcuraTech
Alright I think we've had enough replies for this. All I can say is that nobody has guessed it yet! I forgot to say in the initial diagnosis that when idling in park the throttle response was also poor.

Anyway, the problem turned out to be the TPS sensor! Key on engine off I was getting a little over 2V with the throttle fully closed from the TPS signal output. With throttle closed the signal should have been around .5V.

So the engine thought the throttle was partially open and was dumping fuel accordingly. But the throttle plate was fully closed so it was running rich, hence the smoke and fuel smell from the tailpipe.

So I replaced the TPS with a new DELPHI unit and it was good to go!

This crossed my mind too, but I've never seen one make a vehicle stall out. It makes sense though.

 

[alanu]

I encounter stuff like this at work frequently. Being an auto tech not only is an unrewarding job its commonly a brain teaser and never a cake walk.

try finding a damaged orange wire on a chevy. No input to the computer to trigger the fuel pump. Is it the oil pressure sender? is it a mouse chewing the wire??

fun fun like slamming your nuts in a drawer.

 

[AcuraTech]

Originally Posted By: alanu
I encounter stuff like this at work frequently. Being an auto tech not only is an unrewarding job its commonly a brain teaser and never a cake walk.

try finding a damaged orange wire on a chevy. No input to the computer to trigger the fuel pump. Is it the oil pressure sender? is it a mouse chewing the wire??

fun fun like slamming your nuts in a drawer.


Amazingly enough, this POS beater of a Corsica has been a cakewalk to fix compared to a friend's 99 Acura TL non-POS that I work on frequently.

Example: Looked at the Corsica a few months ago for a similar complaint of stalling out. I went out and started it up and it sputtered and died after a few seconds. Felt like it was running out of gas. Fuel gauge registered 1/8 tank left, well above empty. Before I even popped the hood, I told the owner to put a gallon of gas in it. Lo and behold it fired right up. Ok then, sending unit is bad, no problem. Just dont run the gas tank below 1/4 tank.

99 TL has a slight engine tick at idle, thought it was valve noise. Adjusted valves, still the same. Now thinking it may be piston slap or rod knock. Have had 3 different journeymen old-timer techs in the shop look at it, nobody can come up with any solid answers without an engine tear-down.

F***, this business gets old, I hear you brother! Becoming a mechanic is a great way to make a fun hobby something you hate!

 

[alanu]

I absolutely hate my once loved passion for cars. Thanks "job" you suck

The days of an real oldschool grease money working on 70's v8's will have a difficult time coping with the new tech troubles.

Fords and chevs are my mortgage $$ provider. The new chevs certainly make the benchmark for poor engineering.

Good methodical brain work "acuraTech". Diagnostic skills cannot be taught like spoon feeding a baby. Intuative mindset is what employers want because its a skill many do NOT have. My post "who cares, its fixed" was made because my head hurts thinking of the [censored] I see almost everyday.

People ask why I have to charge 1.5 to 2.5 hours (sometimes 5+ or more) for a so called simple problem. If people could be a fly on a wall they'd be throwing more money at autotechs when they realize the technical skills needed to fix the so called "simplest problems"

Thumbs up "acuraTech" !!

 

[Quest]

Roger that too!

Funny most ole timer mechs are not too far from staring at tombstones these days for they can't even tell if the fuel pump has enough pressure or if it's caused by a bad relay contact on the vane type airflow sensor box. I've came across many of these mechs that all they ever knew is to swap parts until the car worked and then charge the car owners an exorbitant amount of mullahs for the restocking charge imposed on them from aftermarket parts supplier (did I mention lordco or VAP?), or time it took them to get it to working by process of elimination.

Sorry folks, I bailed out of this industry long time ago and wouldn't wanna go back anymore (lack of respect in the field, and also health issues).Although I have work-related health issues even in the IT industry but at least I got the satisfaction in the form of respect I get from serving others.

Keep up the good work folks, we still need you to keep our cars rolling

Q.

BTW: alanu: you in your shop during saturdays? I may ping you and come over for a cup of joe these days...

 

[novaracer69]

there is a torque converter lock up sensor that does the same thing but it is a pain in the as$ if the tps is good then start with a copression test and a leak down test and go from there. It could even be the egr valve or ports plugged.

 

[mechtech2]

TPS?
Great!
But it COULD have been a bunch of things, with those same symptoms.

 

[brianl703]

Yea, how about the 5V reference being off?

 

[alanu]

Originally Posted By: novaracer69
there is a torque converter lock up sensor that does the same thing but it is a pain in the as$ if the tps is good then start with a copression test and a leak down test and go from there. It could even be the egr valve or ports plugged.


Absolutely not. If the EGR is stuck open it'll kill (or prevent the car from idling) or run rough off the getgo. A plugged port will prevent inert exhaust gas from entering the combustion chamber. It will increase NOX but will NOT effect the issue described.

Torque converter lock up issues happen after cruising when the transmission is 1:1 with engine. As you decel it'll stall the engine. Torque converter problems seldom "lock" in park.

 

[alanu]

Originally Posted By: Quest
Roger that too!

Funny most ole timer mechs are not too far from staring at tombstones these days for they can't even tell if the fuel pump has enough pressure or if it's caused by a bad relay contact on the vane type airflow sensor box. I've came across many of these mechs that all they ever knew is to swap parts until the car worked and then charge the car owners an exorbitant amount of mullahs for the restocking charge imposed on them from aftermarket parts supplier (did I mention lordco or VAP?), or time it took them to get it to working by process of elimination.

Sorry folks, I bailed out of this industry long time ago and wouldn't wanna go back anymore (lack of respect in the field, and also health issues).Although I have work-related health issues even in the IT industry but at least I got the satisfaction in the form of respect I get from serving others.

Keep up the good work folks, we still need you to keep our cars rolling

Q.

BTW: alanu: you in your shop during saturdays? I may ping you and come over for a cup of joe these days...


Your not wrenching anymore....... Awesome!!!! There is serious lack of respect in the field. Skilled auto techs are seriously under paid for their knowledge. Sorry to hear about health issues but wrenching for fun is by far more rewarding. Wrenching for $$$ sucks monkey nuts

No saturday work for me. Family time is more important. Coffee always sounds good

 

[benjamming]

Originally Posted By: AcuraTech
99 TL has a slight engine tick at idle, thought it was valve noise. Adjusted valves, still the same. Now thinking it may be piston slap or rod knock. Have had 3 different journeymen old-timer techs in the shop look at it, nobody can come up with any solid answers without an engine tear-down.


injectors i.e. normal?

I respect mechanics a lot & don't understand why folks look down on them. I guess its partly b/c they have/thought they have been screwed i.e. parts monkeys that just change out parts (Quest mentioned). Also, many people just look down at folks that get dirty during a workday. I don't understand that. It is sad as there is a lot of skill required to do the job right (not to mention being a contortionist at times).