I have an 88 audi 90 and the damn idle is bouncing up and down about 20 rpm and sometimes 200 rpm. I have cleaned out the ISV and put some new clamps on hoses to seal up any vacuum leaks. If I rev it up it will then stall after i let off the throttle...... I am getting a little bit frustrated... any ideas???
Check to see if the switch on the throttle body that tells the ECU WOT or closed throttle is working properly.
If you remove the ISV try to blow through it. If it leaks it is bad and needs to be replaced.
Check for more vacuum leaks including your crank case breather hose.
Last night i took the intake off and checked every vacuum hose and clamp, i found a couple of bolts were loose on the throttle body.... tightend it all up and the bouncing went away My idle seems to sit at around 1000 rpm. Also my # 1 cylinder wont seem to be firing every time, i have a new distributer, plugs and wires........ you can hear it missing out the exhaust pretty good too.......???? any ideas????
How do you know it is your #1 and not a different one or randon one misfiring? May be that the coil is going bad or there is arcing by the coil. Worse in morning or night (does dampness affect it? ) Compression check to verify valves?
Steve
Good suggestions. I might add a couple more:
- When dark at night use a spray bottle to mist the plug wires while it is idling. If the wires are bad they will make archs to ground. If the do replace the wires.
- Try a bottle of Techron injector cleaner in a few tanks of gas.
- The I-5 NA engine does tend to make a bit of a puffing sound at the tailpipe when it is running correctly at idle. Might be normal.
When I put the timing light on the light wouldnt flash at a steady pace, it would jump all over the place.
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