crappy idle

[BackTsi]

i just had a new water pump installed on my car and now it idles like a stroked small block. i replaced the plugs and wires since they were crap and no change. it doesn't seem like it misses out nearly as much when accelerating/driving, just at idle. it does occasionally studder when getting back on the gas at shifts under moderate acceleration. any suggestions would be appreciated.

 

[plymouthtalon]

My car had this exact problem one day, and it was a plug. Do you get a CEL? Mine was cyl 1 misfire. Maybe check the injectors or the fuel filter.

 

[BackTsi]

the CEL comes on from time to time, but it did the same before this started

 

[jott5555]

to replace the water pump you have to rip the timeing belt assembly apart. heres where it gets fishy, IF when they reinstalled the timeing belt and parts they could have not set the belt tensioner correctly. which isnt a problem now but in about 3 months when the tensioner relaxes it will jump timeing and start bending valves

so when i had a sopposed "good" shop redo my water pump they did the belt incorrectly. it skipped and cause me 1500 bucks worth of head work and reinstall. but for the 2 months it was running it idled like a chev. on occasion it wouldback fire under higher rpm.. i didnt get a single cel nothing,

so watch it bro...

 

[BackTsi]

I am confident in the pump install since the guy had to get a special tool to do it properly. After driving the car for a couple days, here is an update. The engine only missing when not under load. It drives fine, but misses during shifts and on idle. Could it be TPS or maybe O2? I am going to try possibilites one at a time starting with the most economical.

 

[billdo_83]

what is your vacuum at idle?

 

[BOBS90TURBO]

I had a prob close to yours, very rough idle but ran fine under throttle. I had an intake leak on my manifold gasket, I changed it and it runs as smooth as silk now. Just take a can of stp carb cleaner and spray around possible gasket areas and listen for idle rev or change, if so you got a leak. Or take a piece of vac line and stick one side in your ear and take the other end and trace it around and you will hear sucking sound when you cross the leak(not my fav) GOOD LUCK!

 

[BOBS90TURBO]

Also check your ecu, I had probs like this on my old gst and it ended up being a bad ecu.

 

[Enigma_Man]

You guys are funny It's not the ECU, it's not a manifold problem.

It's very simple. Someone switched his water pump, now he's having problems. Simple cause and effect. The problem is _obviously_ related to the install of the water pump. If someone punched you in the stomach, and you felt sick, would you immediately suspect something you ate?

Whoever was in there would've messed with the timing stuff, so I'd look there first. It sounds like you might've skipped a tooth or something.

-Jesse

 

[racer]

I have someting like that too.I did belt too but that was like year ago,but the problem began like 2 moths ago so Im not sure if that is the reason for it.it lags sometimes when steping on gas at lower rpms and studer too at around 2-2.5 k RPMs. After it goes over 3k it is good.I duno what is it.

 

[jott5555]

humm
what did i say??? people oughta listin to me more....