Idle issues

fr335tyl3r · Post by **fr335tyl3r** » Sun Jan 30, 2005 6:20 pm

Hi guys,

This may be a straight forward issue, but I can't seem to think what would create this problem in the starion off the top of my head.

The problem lies in that when the car is first started and is sitting still, there is no issue with idle (sits around 800 rpm or so). If the car is rev'd up any amount from idle, it will go up smootly, but when it drops back it will crash down to about 200rpm idle and then slowly (over about 2 or 3 seconds) rev back up to 800rpm by itself.

This is not a problem when we just rev the car in the driveway, but out on the road, if the car is running and this happens as we pull up to traffic lights (this idle issue obviously only occurs in neutral or with clutch fully in), it seems that occasionally the car will stall when it comes to a stop, which is bad.

Any ideas on what may cause this issue or what may rectify it? If it helps, the oil pressure guage on the dash shows the needle sitting right on the L line while idling and about 1/4 of the guage higher at most when driving.

Thanks guys.

Junkers · Post by **Junkers** » Sun Jan 30, 2005 6:52 pm

My old starion did this also but not as bad, once it stalled when i put the brakes on really heavily coming into my driveway.
It could be something like a worn throttle position sensor, maybe.

Defective · Post by **Defective** » Sun Jan 30, 2005 6:57 pm

yep, mine did the same thing, never worried me enough to think about fixing it.

Powerslave · Post by **Powerslave** » Sun Jan 30, 2005 7:24 pm

It's probably a hole in the dashpot diaphraghm on the throttlebody. If you remove the opposing end of the hose going to it , try sucking on it , (this is not a joke BTW) , if the vaccuum stays , it's OK , if it leaks , it's fucked. These cannot be repaired. There is also an adjustment screw on it , try adjusting it if the diaphraghm is ok. To adjust it , lift the actuating arm which should bring the idle up to about 1200-1500 rpm. Then release it , timing how long it takes to return to normal idle. 3 seconds is usually on the money. This is not specific to starions , but all carburetted and all throttlebody injected cars that do not have ISC motors. This was an issue with my starion also early in the piece , mine had a leaky diaphraghm. I swapped it with a spare that I had , but it only marginally improved it. Further adjustment fixed this problem totally. I can post pics if required.

:beer

fr335tyl3r · Post by **fr335tyl3r** » Sun Jan 30, 2005 7:33 pm

Pics would be good powerslave.

But how would this explain the fact that the car idle'd fine at the start of the trip (1-2 hrs earlier) and then by the end of the trip it was no good?

Cookiemonster · Post by **Cookiemonster** » Sun Jan 30, 2005 8:05 pm

This bit:

fr335tyl3r · Post by **fr335tyl3r** » Sun Jan 30, 2005 8:09 pm

Thanks cookie and powerslave for the info. i will try that tommorrow morning. :)

fr335tyl3r · Post by **fr335tyl3r** » Mon Jan 31, 2005 11:21 am

Cookie or others....as my car is a JB and has a slightly different Intake Manifold n throttle body, do you have a picture of where this part is on the JB? I had a quick duck around and couldnt see it.

Junkers · Post by **Junkers** » Mon Jan 31, 2005 1:49 pm

Does it still have the black or red ECI logo on the top of it or does it look completely different?

fr335tyl3r · Post by **fr335tyl3r** » Mon Jan 31, 2005 1:58 pm

completely different. it is the jb/jd style one that does not have the eci logo on top

Fuel · Post by **Fuel** » Wed Feb 02, 2005 12:07 pm

JB has an ISC motor in the same location, disconnect it, see what happens then.

fr335tyl3r · Post by **fr335tyl3r** » Thu Feb 03, 2005 7:08 pm

Update on above: I thought that the blow off valve could be the culprit as I did the following test during the day today.

1a. Reving in neutral to under 3k rpm
1b. Reving in neutral to over 3k rpm

2a. Running in gear and changing before 3k rpm
2b. Running in gear and changing after 3k rpm

3a. Running in gear and clutching in without gear change before 3k rpm
3b. Running in gear and clutching in without gear change after 3k rpm

The problem that occurs (ie, after accell taken off, revs drop to 100-200 rpm instead of idle and slowly creep back up) only occurs in situation 3b really. It would occur in 2b but as the gear change happens revs dont have time to drop off.

In 1a, 1b, 2a and 2b the revs settle at idle as per normal (no boost is made).

As stated above I thought the bov may be culprit so I removed the BOV and replaced it with a different one, same problem. Then i clamped the vacuum hose to the bov and disconnected the tube from the BOV so that it would not blow off, still same problem.

Any ideas what could be the cause of this still? I am going to swap the map sensor over from another car incase that is the culprit. Just to clarify, the car drives PERFECT under all other conditions except when it has boosted, u let off the accel and get on the clutch.

Any help would be appreciated. I will be changing to MPI as soon as I have the money to do so, but would like to get this fixed. My mechanic had a look and he couldnt find the source of the problem.

Thanks guys

Cookiemonster · Post by **Cookiemonster** » Thu Feb 03, 2005 7:34 pm

Take the easy route.. go MPI and problem solved.

fr335tyl3r · Post by **fr335tyl3r** » Fri Feb 04, 2005 12:20 am

Yeh im looking at that now cooks. Just need to get rid of some of the debt worked up to buy this car first :)

Austarion

Idle issues

Idle issues

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