9 replies to this topic

[coyttl]

Hey guys! (I know, I'm from the US. Be good to me, I'm not typical! ) Have an '92 SPi, that once so far idled really strangely.

Background - Every so often, the engine would stall. Once stranded me on the side of the road, the other times while working on it in the driveway. When it stalled it wouldn't start, just turn over. At a random point afterwards, it'd turn over and just fire right up. Each time it happened, the engine would 'fix' itself before I could find out whether it was fuel related or spark.

So, after replacing a vacuum hose yesterday (different issue), I decided to tear up a local road. Drove hard, soft, down-shifted, coasted, you name it. Ran perfectly fine. As I pull into the driveway, I noticed it idling funny: Starting at around 1k RPM, it would raise up to 2k, then drop back to 1k and repeat the process. Took perhaps.. 2 seconds for a cycle like that. While it was doing this, I opened the bonnet to peer at the steper motor - however it was too dark out and didn't have a flashlight handy. Turning off the ignition and restarting it, it idled fine.

To me, sounds like the stepper motor was either 'stuck on' or the ECU was flaking out. :/ Thoughts?

[duncancallum]

id check the plug on the stepper fist to make sure its ok and not loose

also at the risk of getting flamed mine was doing something similar n i got told to put the igntion on and pump the throttle 10 times you should then hear the stepper adjust up

is it ok on fuel because it could be other isuses as well

[coyttl]

id check the plug on the stepper fist to make sure its ok and not loose

also at the risk of getting flamed mine was doing something similar n i got told to put the igntion on and pump the throttle 10 times you should then hear the stepper adjust up

is it ok on fuel because it could be other isuses as well

Never messed with teh stepper motor (yet) so I'll be careful around there. I do hjave an issue with the fuel pump turning off while it's supposed to be on (will be troubleshooting that more today), but when it did this, it was fine...

[duncancallum]

your fuel pump may be due to a iffy cut off switch mine gave me a load of bother

[imabitnaughtyxx]

possibly airflow meter, i assume they are fitted to spi's, they are the route of 90% of idling and stalling problems in injection cars.

[coyttl]

your fuel pump may be due to a iffy cut off switch mine gave me a load of bother

This may be it - I took mine off the yesterday, cleaned the contacts, cleaned inside the weatherproof rubber, and reassembled. Didn't have an issue all day yesterday. I'll be taking it into the office Tuesday, so that'll be the real test.

[coyttl]

possibly airflow meter, i assume they are fitted to spi's, they are the route of 90% of idling and stalling problems in injection cars.

I dunno if we have a /flow/ sensor. I know I have an incoming air temp sensor. I'm in the process of getting a code reader for the little SPi, and I'm curious to see what that turns up.

Cheers,
Mike.

[duncancallum]

spi and mpi dont run airflows they use a map sensor and an inlet temp sender

[imabitnaughtyxx]

spi and mpi dont run airflows they use a map sensor and an inlet temp sender

but at a guess cause idling problems in much the same way, does it have an automatic choke fitted by any chance?

[coyttl]

spi and mpi dont run airflows they use a map sensor and an inlet temp sender

but at a guess cause idling problems in much the same way, does it have an automatic choke fitted by any chance?

Nah. The ECU controls the idle speed with a stepper motor. (I guess.. in a sense, it could be called 'automatic choke'. ) I verified operation of the stepper yesterday by opening the throttle without moving the pedal (leaving the throttle switch closed) - when releasing it, it bounced back, and the stepper motor adjusted it as necessary.

Haven't been able to recreate it since - nor get the lack-of-fuel issue. Which means I need to start driving it again to get it to fail.