8 replies to this topic

[RooBoonix]

Hi everyone,

 

First of all, I know what your first thoughts are, "use the search". I have. This thread is merely to help me make sure I have all bases covered and so I'm not going to miss anything during my checks tomorrow. The car is a 1994 Rover SPi.

 

Here's the story... I had an RC40 exhaust which I have replaced for a stock/standard exhaust (for insurance reasons, I'm 16, 17 next Monday), whilst testing exhaust car ran fine, a water hose split and the exhaust was drooping a little low. So I loosened the CAT - Rear section bolts jacked the CAT up a bit and tightened the bolts again, made it sit a little higher, I was happy. New water hose came got it all fitted and today I went about bleeding the air.

 

So I started the car, rad cap off and I did think it was revving a little high but I just left it, added some anti freeze mix and all seemed good, but for some reason it won't idle below about 1500rpm. Blip the throttle it revs fine and settles quickly back down to 1500-1600rpm. Took the airbox off, butterfly seems to move freely and back to it's original position. That's where I left it as I had football training to go to.

 

So I've been googling and have came up with some chores to do tomorrow to check it over and try and find the problem. Here's a list... Check throttle cable is seated properly and is adjusted properly, reset TPS (ign. 2 and pump 10 times), check vacuum lines from airbox through to ECU for leaks, clean and check for cracks in IACV, test Lambda sensor readings (I have a Gunson Lambda sensor tester in the shed so hopefully that will be alright for that), and that's where I've got to... 

 

So, are there any other sensors to check? Any bits of wiring which may be causing a problem? Am I right in saying one of the yellow relays in the top right of the engine bay have something to do with the O2 sensor? I'll clean the contacts anyway...

 

Thanks in advance,

Cam.

[minisilverbullet]

you seem to have all the essentials covered. 

 

When you check the vacuum lines, take them off and inspect them closely. 

[RooBoonix]

you seem to have all the essentials covered. 

 

When you check the vacuum lines, take them off and inspect them closely. 

 

Thanks, that's reassuring. I fitted silicone vacuum lines not too long ago so they SHOULD be alright but i'll check either way. My vacuum gauge still shows good vacuum but I don't know

 

Cam.

[jaydee]

You have an air leak somewhere, check everything accurately, it will require patience, it took me two hours to find the source of an air leak once, and it was the vacuum servo having a small leak..not the most obvious thing to check on the spi.

[RooBoonix]

Ok ill check that out, thanks

[RooBoonix]

All fixed nice and easy. Stepper motor had come unplugged so was hunting around 1500rpm all the time. Plugged it back in and all smooth again. Must have knocked it when I replaced the inlet to sandwich plate water hose.

 

 

Thanks for the help guys,

Cam.

[brivinci]

Rather then start a new thread, I'm dragging this up.

 

My 94 just started to do this. Was running like a top until the other day. It happened to be after I washed it finally. Maybe it likes to be dirty:-) Anyway, start the car cold and it idles around 1k but then raises slowly to 1500k. I drove it to work today (about 20 minutes of back roads) and it idled as high as 2k at one point. By the time I got to my office, it would rest back down at 1k. Typically, it idles around 800k. I know I have to check the vac lines. All but one have been replaced with silicone. The only one that has not is the red one that goes from the box to the back of the manifold. That one I replaced with a brand new OEM unit at some point. I would think the silicone lines are good but I will check non the less.

 

I do not have access to the scanner as I am in the USA but can get one sent to me from a friend in Florida. Might have to do that if I dont find any leaks. I did replace the grommet that seals the outlet for the vac off the brake servo. Not even sure how I would test for a leak there. I guess I'll check that the stepper motor is plugged in correctly as well.

[RooBoonix]

I replaced my brake servo grommet too, I found that levering on the pipe slightly could cause a change with my old grommet. If I levered the pipe at the servo outwards the idle would rise and not be as smooth, if I pressed it in it would return back and idle as normal. With the new grommet it is a much better fit and this isn't possible. Definitely check all vacuum lines, I've replaced all of mine with silicone and have had no problems with them. Stepper motor is very easy to check, it's on the front right side of the inlet. Might have to take the air box off to see it I can't remember exactly. Might be worth using some electrical cleaner too just for the hell of it.

 

Also, make sure your throttle cable is moving freely and that the pedal isn't obstructed. I had a problem where my wheel arch carpet was stopping the accelerator pedal from springing back fully so it would hold the idle slightly high.

 

Hope that helps and you find your problem!

Cam.

[brivinci]

On my the way home from work, the car ran much better. Sorry, not that is runs poorly, just the idle I mean. The revs would fall to about 1500 and then a bit slower to the 1k. Seems to idle around 900 now but doesnt always fall back directly to that point. I am going to pull off the airbox, remove and inspect all silicone lines and the last remaining stock line and make sure they are all perfect. Then disconnect and clean all contacts for MAP and stepper and anything else, just to be safe.