Friend seeks help, Civic stalling.

[slowrider87]

So my friend at work drives a 98 civic sedan autotragic, 170,xxx miles,
Not sure what the Engine model is cuz the block was so oxidized i couldn't see the casting number. oh well, who cares.

Problem: She tells me that the car starts and runs fine until it reaches operating temperature, then the car starts to stall and trys to shut off unless she gives it some gas, which is another problem, she says the throttle/pedal gets really stiff when it happens.

I know stalling is generally based on fuel or air (or lack there of) so i checked what i could in a poorly lit parking garage at midnight when we got off.

intake is sucking air in like normal, stronger vacuum with more throttle
new filter, wires, plugs last week. (no problem before this, gapped wrong?)
Exhaust is exiting normally

It's not over heating i sat there for 30 mins and checked the temp gage periodically the whole time.

Any ideas? she said someone told her it may be the tranny itself.

all help is appreciated. shes a cook and gives me free pizzas all the time so i feel like i should help as much as possible.

 

[Tphong]

could be a starter problem. I had a similar problem with my girls integra with the stalling except it didn't need to get to operating temp. Could try checking battery voltage possibly the car isn't igniting the fuel. don't know about the throttle

 

[ib042129]

Throttle getting stiff? I don't get how that would happen. The pedal is just connected to a butterfly valve. There is no mechanism for it to get stiffer.

I had a problem with idling when I connected my gas tank vent tube incorrectly. Basically after a fill-up the engine would get too much gasoline in it and not idle unless I kept the gas up. So, could be the same thing probably in the form of a leaking injector.

Or. Alternatively there could be a big vacuum leak.

So check if the engine is running rich, or lean. And check that all the vacuum hoses are connected. (If it's running rich you could smell the gasoline. But you can aslo just measure the voltage on the oxygen sensor to tell you at Air/Fuel mixture. )

 

[knighthawk1104]

It's less vacuum with more throttle because the plate opens up. when the plate is closed you get maximum vacuum.

Check if the cat is clogged.

 

[DarkSideAccord]

clogged catalytic convertor... same thing happened to me last week... to check, just put ur hand near the exhaust tip.. if lil to no air is coming out, it's a clogged cat

 

[knighthawk1104]

clogged catalytic convertor... same thing happened to me last week... to check, just put ur hand near the exhaust tip.. if lil to no air is coming out, it's a clogged cat

he said it's exiting correctly. i believe he check that already.

 

[nsjames]

the get's to operating temp part is the key. That's whn the ECU goes cosed loop. I'd suspect O2 sensors, malfunctioning EGR or a vacuum leak that shows up when the metal parts get hot. IF there's no codes I would suspect vacuum leak first, especially check where te PCV elbow is.

to really check out the intake manifold get a propane torch, don't light it, and fog all of the vaccum harness/intake manifold flange. DOn't blow yourself up. When you find the leak the motor will stall from the overly rich mixture.

 

[slowrider87]

could be a starter problem. I had a similar problem with my girls integra with the stalling except it didn't need to get to operating temp. Could try checking battery voltage possibly the car isn't igniting the fuel. don't know about the throttle

it can't be a starter problem if the car is already running and up to operating temp. once the car starts the starter just sits there doing virtually nothing. battery is good.

Throttle getting stiff? I don't get how that would happen. The pedal is just connected to a butterfly valve. There is no mechanism for it to get stiffer.

seemed odd to me too. i didn't drive it so i don't know if thats really the case or shes convincing herself of something thats not happening.

It's less vacuum with more throttle because the plate opens up. when the plate is closed you get maximum vacuum.
.

you're right. i'm backwards. just talked based off of sticking my hand over the intake, hitting the throttle, and feeling more suction at the inlet. twisted my head up. but yeah your right.

clogged catalytic convertor... same thing happened to me last week... to check, just put ur hand near the exhaust tip.. if lil to no air is coming out, it's a clogged cat

he said it's exiting correctly. i believe he check that already.

yeah i checked it. that was one of the first because i remembered your thread about it, darksideaccord.


heres a thought i had.i figure since she had new plugs wires and **** put in to look around those, for things that could have been bumped while doing the work.

Also, the intake airbox is sitting on top of the throttle body. so perhaps when the new filter was put in it could have knocked some dirt or something onto the throttle plate, and since the throttle gets stiff but only once the cars heats up means there could be something heat sensitive that could become sticky when heated up by the coolant that runs through the throttle body. possibly causing the throttle plate to stick closed, so when pushing on the pedal it may still be dump fuel in but not have enough air to burn it, or keep the car running. It's mechanically possible. sound good to anyone else? because I just pulled all that out of my *** right now.

...actually, the TPS sensor wouldn't read any air, therefore causing the wrong amount of fuel for the engine to keep going at speed? idk..

input?

 

[ib042129]

I guess I will say it again and suggest you check all the vacuum connections. You might be having a vacuum leak because the guys servicing the car forgot to plug some line back in, or knocked off a vacuum plug or something.
This has happened to me before with the shop tuning my car leaving a small vacuum connection open. It resulted in really rough idle and occasionally stalling the car.

If the sticky/heavier throttle is indeed a real thing, then you should probably also inspect the throttle plate and see if there is crap in it. (But if I remember TB has a separate passage just for idling. It bypasses the throttle plate. At least on my car I think that exists.)

And maybe in general check if the engine runs rich or lean. Check if the plugs are wet, or just measure the O2 sensor voltage.

 

[ib042129]

to really check out the intake manifold get a propane torch, don't light it, and fog all of the vaccum harness/intake manifold flange. DOn't blow yourself up. When you find the leak the motor will stall from the overly rich mixture.

That's clever, but sounds scary as hell.