another idle thread

[long tall eta]

i get this surging idle thig going on. and befoer you all scream vacume leak, i don't think it is. i checked all around both visually and w/ carb cleaner. my idle jumps from 600 to 800 in a rythmic surge. dosent do it all the time. when i first start her up she is at a steady 900 for about 3 to 4 minutes then drops to the surge. i can hold the peddle and keep her at the 700 idle with slight pressure. the warmer it gets the less it happens. if it was vacume wouldn't it do it all the time. cleand the tb, and icv. could it be the tps? and is there a way to adjust that while on the car. how do u get underneith the tb to adjust while on car? it's an 86 eta.

[Victor_PR]

I had the exact same problem with an '87 Eta I had. I never did find the root cause however I noticed that as I squeezed the vacuum hose that connected to the ICV the fluctuation (similar to what you describe) was eliminated. My cheap homemade fix was to drill a 1/4" hole in a penny and put it inside the hose.:p
Hey, it worked and I was able to sell the car.
Another thing you can check is the Temp Sender in your thermostat housing.
Good luck!

i get this surging idle thig going on. and befoer you all scream vacume leak, i don't think it is. i checked all around both visually and w/ carb cleaner. my idle jumps from 600 to 800 in a rythmic surge. dosent do it all the time. when i first start her up she is at a steady 900 for about 3 to 4 minutes then drops to the surge. i can hold the peddle and keep her at the 700 idle with slight pressure. the warmer it gets the less it happens. if it was vacume wouldn't it do it all the time. cleand the tb, and icv. could it be the tps? and is there a way to adjust that while on the car. how do u get underneith the tb to adjust while on car? it's an 86 eta.

[jlevie]

i get this surging idle thig going on. and befoer you all scream vacume leak, i don't think it is. i checked all around both visually and w/ carb cleaner.

Which only means that there wasn't a large leak in a place that carb cleaner will work (close to the head) and which you can reach. The only way to know if there are intake leaks and where they are is to have a smoke test run. There are plenty of other possibilities, but until intake leaks are ruled out it is pointless to consider those.

[long tall eta]

Which only means that there wasn't a large leak in a place that carb cleaner will work (close to the head) and which you can reach. The only way to know if there are intake leaks and where they are is to have a smoke test run. There are plenty of other possibilities, but until intake leaks are ruled out it is pointless to consider those.

i hear ya on the leeks, but what would cause the problem to be intermitant? if it is a vacume leak, what is sealing it up half the time i drive the car? wouldn't the leak be present all the time causing the fluctuation to occur all the time?

[Kozworth]

Just the engine moving down the road, plenty of vibrations and moving parts could exfoliate or hide a vacuum leak.

Just one quick thing id recommend is wiggle the harness going to the iac. On a friends eta, the wires were hardly making contact in the harness to the iac, so sometimes it would hunt for idle and other times it would be fine. Id just check that and then go smoke test it.

[dnguyen1963]

The elbows going into the throttle body can come loose and tighten up with the vibrations from the engine...There are plenty other places for vacuum leaks that carb fluid would never find.

[long tall eta]

i hear u guys on the vac leaks, but if it is a vac leak, why dosen't it do it all the time? what comes along and seals it up half the time? with slight pressure on the accelarator peddle, i can hold a butter smooth 700 rpm's. if it was a leak, wouldn't it still be ruff?

[dnguyen1963]

Depressing the gas pedal might have forced a correct fuel:air ratio; thus smoothing out the idle. This is highly indicative of vacuum leak.

[hashi]

i get this surging idle thig going on. and befoer you all scream vacume leak, i don't think it is. i checked all around both visually and w/ carb cleaner. my idle jumps from 600 to 800 in a rythmic surge. dosent do it all the time. when i first start her up she is at a steady 900 for about 3 to 4 minutes then drops to the surge. i can hold the peddle and keep her at the 700 idle with slight pressure. the warmer it gets the less it happens. if it was vacume wouldn't it do it all the time. cleand the tb, and icv. could it be the tps? and is there a way to adjust that while on the car. how do u get underneith the tb to adjust while on car? it's an 86 eta.

Try cleaning the ICV and check the temp sensor

[bddog]

surging idle. ICV

[harold30]

if you don't believe you have vacuum leaks try cleaning your icv and adjust your tps to spec.

i had this problem before and it took me a whole year to fix the annoying idle because I was stupid to believe that it wasn't a vacuum leak and oh, i used carb cleaner too, then i changed almost everything that related to fuel preparation and intake that didn't needs to and it cost me a lot resulting from not following jlevie's suggestions (if you search the list of things to do). if you do smoke test first then you can minimize your expenses and only change those parts that shows a problem. if you don't wan't to spend for a shop's smoke test you can search on youtube for d.i.y smoke test that will do as long as it has a correct smoke psi and it would only cost you a fraction. hth

[nickmcc92]

Intake leak, icv or afm.
Try sea foaming it.
& don't adjust anything.

[bmwstudent]

Bob, if you bring her down to me I can smoke it for you. I have access to a smoke machine.

[long tall eta]

Bob, if you bring her down to me I can smoke it for you. I have access to a smoke machine.

sounds great but cant till next week. can u do a mon, tues, or weds?

[bmwstudent]

let me talk to my buddy, i may be able to get it one night this week.