clio

My car (1999 year) has suffered a range of problems including an inconsistent idle, on occasion stalling, small but distinguishable stutters when accelerating.

This is what I have done to try and fix the problem:

- replace primary o2 sensor with new unit
- replace map sensor
- pull apart idle control valve (remove motor from valve and spin to ensure it revolves smoothly)

My car is stock (apart from suspension), spark plugs are good, valves were adjusted a couple of years ago.

The funny thing is sometimes the car will run perfectly and the next time it's driven the issues will re-appear.

Any suggestions appreciated.

dagle

Do you engine brake to a stop regularly, or do you step into neutral and coast to a stop?

If you neutral coast to a stop, that's likely the cause for your specific model year.


If not, you may want to do a compression test and follow up by inspecting the valve retainers. The valve retainers crack prematurely on AP1's and may cause phantom stalling issues, but it's rare to show no other symptoms.

clio

I don't usually coast to a standstill. I know ap1's are prone to cracking intake retainers but from what I read this issue is closely related to a mechanical over-rev (which I haven't done), and I cannot find any reference to cracked retainers causing issues similar to what I have experienced. In fact cracked retainers seem to have no symptoms until it all lets go.
Because the problems are intermittent I'm also doubtful it is a compression issue.

Aggie_Grad_12

I would do a compression test. I had the same issue and cured the stalling a few months ago with a MAP wack and ECU reset but it still idled a little rough. Last week I got a misfire code. I just did a compression test last night and got 220 110 220 225. Working on tracking down the problem on cylinder 2 tonight.

dagle

Well, instead of discussing on a forum of what you think it is or isn't, why don't you find out by confirming first? Theoretical discussions for the leading theory as to why your car stalls intermittently won't really get us anywhere.

In order of things I would personally check given that I've troubleshot your issue before: (I've now had 3 AP1's, 1 AP2 and currently own a 2.2L F20C with an AP1 head using AP1 sensors and fuel system.)
MAP sensor
ECU
valvetrain wear/failure / compression issue
intake manifold issue (TPS, air plumbing, etc.)
fuel system
spark/timing related electronics gremlin

clio

OK thanks - I haven't reset the ecu before or thought of the tps so will give those a go and move from there.

clio

I zip tied the map sensor connection and reset the ecu by removing 'back up' fuse for a few minutes. I've subsequently driven the car twice and it runs and idles perfectly. I'm not 100% sure what the cure was;
- 02 sensor replaced a couple of days ago and perhaps the ecu reset helped to adjust to it (?)
- the map sensor connection was dodgy (a known issue)
- the ecu reset in isolation helped
Regardless it's seemingly all good now.