Couldn't resist to ask... idle issue...

[spencerxog]

I know i know that I shouldn't be posting such a stupid rookie question.. but I am losing my marbles with this... 98 audi a4 1.8t manual basically stock just a tune... anyways I can't even drive my car because the idle is so bad.. it will settle out after letting it run but if you give it gas and let off the rpm drops and sttuwrs and comes back up then drop amd about to die and a lot of times it will die only after starting it or giving it a little gas.. what baffles me is I've replaced everything almost and checked everything.. I replaced coils plugs icm maf cleaned throttle body.. done everything there's no boost leaks guaranteed.. checked all Boost lines about a good 10 different times even with soap.... it's been literally sitting for months and still no luck:/

[kenncmiller]

Does it drive fine when not at idle?


Sent from my iPhone using Audizine

[LA4]

Throttle body alignment?

You say you've checked all the vacuum lines, have you checked the intake manifold gasket?

What's the fuel pressure like when it's acting up?

[spencerxog]

Throttle body alignment?

You say you've checked all the vacuum lines, have you checked the intake manifold gasket?

What's the fuel pressure like when it's acting up?

It bucks when I drive it hard to remember becsuse I havnt drove it so long but yes I have done throttle body alignment and Intake gasket is new and sealed ... fuel pressure I'm not sure I would have to check that when I csn and Ile get back to you.. fuel injector 1 was leaking, changed o rings and no leaks.. runs a little better but really no difference

[walky_talky20]

1 - Have you checked for codes with VCDS (not a generic scan tool, actual VCDS or VCDS-Lite)?
2 - What is the fuel trim data from measuring block 032? (additive(idle) and multiplicative(part throttle) fuel trim data will tell us a lot here)
3 - What do the spark plugs look like after reaching operating temp?
4 - Does it run better or worse with the MAF unplugged?
5 - How does the exhaust seem to you? Dark, smelly, raw fuel, flames, etc? Or does it seem like it's hardly getting fuel?


Sounds like you may have an fuel mixture issue. I'm thinking it may be running very rich, perhaps a faulty coolant temp sensor (reading very cold in error) or incorrect fuel pressure. Just 2 initial guesses. Your answers to the 5 above questions will help.

[spencerxog]

1 - Have you checked for codes with VCDS (not a generic scan tool, actual VCDS or VCDS-Lite)?
2 - What is the fuel trim data from measuring block 032? (additive(idle) and multiplicative(part throttle) fuel trim data will tell us a lot here)
3 - What do the spark plugs look like after reaching operating temp?
4 - Does it run better or worse with the MAF unplugged?
5 - How does the exhaust seem to you? Dark, smelly, raw fuel, flames, etc? Or does it seem like it's hardly getting fuel?


Sounds like you may have an fuel mixture issue. I'm thinking it may be running very rich, perhaps a faulty coolant temp sensor (reading very cold in error) or incorrect fuel pressure. Just 2 initial guesses. Your answers to the 5 above questions will help.

1. No I don't have one and should invest into one.
3 dark just changed with ngk bkr7e or whatever there called no difference...
4. No difference.
5. Raw a little...
I finally drove it after it being parked so long and it drives fine until you slow down the rpms bounce down and it will die if you don't keep revving it... so just an Idle issue

[OverSpun]

Did you check and/or change your check valves and also the jet suction pump? Those can cause a rough idle.

If you have not checked your coilpacks too...

[walky_talky20]

You need VCDS so you can at least read the codes and see instant trims.

There is almost no investment. VCDS is literally free, you just need a $5 cable. Then just beg, borrow or steal a crappy laptop.


VCDS for *actual* freezies right here

The VCDS Cable you need for less than 5 bucks shipped. Yes, this is real. Yes, this is really happening.

Need a laptop to run this junk? Clicky.

[spencerxog]

Wow I was thinking they were around 3 and I just bought one this morning so it should be here Wednesdayish.. and I will get back to you guys and yes all check valves are brand new.. even checked on a diagram online to make sure..

- - - Updated - - -

Wow I was thinking they were around 3 and I just bought one this morning so it should be here Wednesdayish.. and I will get back to you guys and yes all check valves are brand new.. even checked on a diagram online to make sure..

300...

[gtsingh91]

You mention no change when you unplugged your MAF. I had an idle issue that turned out to be my MAF sensor. Did you swap that with a new OEM one?

[audinutt]

Are you sure it's not your tune?
Has it always done this?

do you have access to vcds/vagcom?

[spencerxog]

No I have not.. waiting for it to come in the mail now.. and yes it was an oem Bosche maf.. now I ran into another issue after driving the car... I finally pulled into my driveway and it immediately died when I slowed down to a stop and so I let it sit for a couple seconds after starting it and now it won't start and backfires sometimes through the intake... I'm almost done putting some stuff back togeher after taking some things apart and going through leaks and etc.. I had a small oil leak out my fitting on my turbo and fixed that... I checked timing and Timing is fine both on cams and bely along with injectors noticed cinder 4 had a little oil from leaking valve cover so I'm going about to the parts store in a bit for a new valve cover.. going to do a compression test and leak down in a bit and report back after I get my vc gasket

[spencerxog]

You need VCDS so you can at least read the codes and see instant trims.

There is almost no investment. VCDS is literally free, you just need a $5 cable. Then just beg, borrow or steal a crappy laptop.


VCDS for *actual* freezies right here

The VCDS Cable you need for less than 5 bucks shipped. Yes, this is real. Yes, this is really happening.

Need a laptop to run this junk? Clicky.

Fixed idle.. I was give the wrong 02 sensor and ended up buying the correct one to fix the issue and now I'm having issues with the car again.. it won't start anymore ever since I put gas in it since it sat... I drove it around for a bit and finally came home pulled into the driveway pulled the e brake and immediately died.. found out the injectors are not pulsing when turned key but fuel is going to fuel rail becsuse the hose is very pressurized and if I wiggle the injector it squirts out gas.. any thoughts.. I reslly think the pressure is fine but I'm still waiting for my vag cable to arrive.. even scanned the car with a super nice Bosche scanner from my works mechanic

[walky_talky20]

Sounds like the crank sensor (aka engine speed sensor, aka RPM sensor) might have died. They are known to die sometimes. Usually they get temperamental first where they conk out when they/re hot, but work again after cool down. Often creates a "hot restart" problem at first, which usually manifests as an "I'm stuck at the grocery store for an hour" problem.

It is very common in the above situation for it to show zero codes on a generic scan tool, but show an "intermittent" code for faulty crank sensor signal only when scanned with VCDS or VW/Audi dealer scan tool.

That's just one possibility, though. Could be an open wire in the harness such that all the injectors lost power, bad ECU, etc.

[spencerxog]

Sounds like the crank sensor (aka engine speed sensor, aka RPM sensor) might have died. They are known to die sometimes. Usually they get temperamental first where they conk out when they/re hot, but work again after cool down. Often creates a "hot restart" problem at first, which usually manifests as an "I'm stuck at the grocery store for an hour" problem.

It is very common in the above situation for it to show zero codes on a generic scan tool, but show an "intermittent" code for faulty crank sensor signal only when scanned with VCDS or VW/Audi dealer scan tool.

That's just one possibility, though. Could be an open wire in the harness such that all the injectors lost power, bad ECU, etc.

Okay I thought all the injectors are all separately powered so it seems impossible for that to be a wiring issue.. as far as the crsnk sensor that might be a good try as I had a bad coolant leak I had to fix from over tighten clamped on the oil cooler.. which went straight to the sensor so Ile get back to you after I buy a new sensor tommorow..