Motors I'm building my own car... UPDATE - Stoneliegh 2013

Hi quality vinyl - as the car is never going to have a roof, it's inevatibly going to get wet at some point. I didn't what to go to the expense of leather only for it to get trashed later on.

I'm also not feeling so light now.

Merlin have rung me to advise that I should really go for the SuperSport version of the belts with the normal style seatbelt catch, as the IVA man wouldn't like the aircraft style buckle.

Apparently the MOT testers don't like them either... Which is a shame, as I do. Boo.

Anyway - I've gone with their suggestion, but the upside is they're considerably cheaper!

 

Fair choice if the vinyl is nice - it can make very nice seats indeed, and it's nice if, as you say, it gets piss-wet through one day.

 

Agree about the vinyl. Not sure how the port coloured seats would go the BRG body colour though?

Surely the seats would only get piss-wet if the brakes fail?

 

I think Port + BRG would look awesome, especially with those chromed exhausts too.

 

I've been busy wiring up the dash, and I believe I may have found an issue. The rev counter reads 2K RPM at idle. Thinking there might be something wrong with the gauge, I hooked up my multi-meter to the coil and looked at the tach on that - and it agrees!

The normal idle revs should be somewhere between 750 and 800 rpm.

I guess that answers some of your questions as to why it sounded as if it was being revved hard on the video - it was...

Apparently, culprits for this behaviour are any of following:

1. The coolant temp sensor being on the blink
2. A vaccumm leak
3. The AFM not reading correctly
4. The throttle position sensor not reading correctly
5. The Idle bypass valve being up the spout.

I don't think it's 2 or 5, as I cant see anything wrong with the vac lines, and I can't feel anything around the brake servo. The bypass valve is working, as I can hear it buzzing when I turn the ignition on - just as the manual says it should.

I think I'll try changing the temp sensor first - it looks as if it the original one from the factory, so it's pretty old and wont hurt to replace it anyway. If that's not it, I'll have to spend some more time with the multi meter taking readings on the sensors and see if any of them are duff.

 

Just turn down the idle screw on the carb...

Just kidding, I hope its something simple GOO.

 

Uh oh... I'm sure you'll sort it GOO.

 

Our 1971 Chevelle for some reason also says it idles at 2000 rpm, which we know to be obviously false .

Still haven't fixed it sadly, we think it might be that we have the wrong sending unit for the tach that we have. So I'll be interested to see what the culprit is good luck!

 

I would put it down to a faulty AFM, have you tried disconnecting it to see?

 

Well, I've got it idling at 1K rpm now. Turns out that when I stripped and cleaned the throttle, I didn't "calibrate" the Throttle Position Sensor (read: bolt it back on in the right position ) when I put it back on.

The TPS has some adjustment in it as you can turn it on it's axis either clockwise or anticlockwise when you mount it. As it was a bit skewed, the throttle closed / idle switch in the TPS was never closing, and the ECU thought the throttle was open all the time even when it wasn't.

It's still a bit high, but a big improvement.

I've also checked the ECU temp sensor, and I think it might be buggered. It doesn't match any of the resistance ranges in the workshop manual. I guess I'll be calling the BMW parts desk again on Tuesday.

 

Glad to see you have it sorted, especially with a nice simple fix!

I would've said exactly the same as Xeno though, what knowing nothing about electronically controlled engines ECUs and engine management malarkey!

 

Most tachos either take a feed from the neg. side of the coil, the alternator or a dedicated feed from the ECU...

I'm guessing with a car that old, It'll just be a feed from the coil - no sender involved.

 

Is there an idle adjust screw on the IACV - idle air control valve?

I know on my car, the idle can be adjusted by either the IACV, or by a screw on the throttle body (for mechanical throttle linkage)

 

No - there are on the 318i engines, but the 325i (M20B25) have a different ICV that has no adjustment.

There is an adjuster for the throttle stop, but this is set correctly (a gap of 0.015 inches between the butterfly valve and the housing.)

I'm going to go fit the new ECU coolant temp sensor and give the ICV a blast with some Carb cleaner just in case it's got gummed up since I cleaned it last.

 

Hmmm - ok, cleaned the ICV again (not that it was dirty anyway), and replaced the sensor. Revs still the same though.

Ah well - it's not a big issue. I wonder if there is a period of the ECU relearning settings?

 

Quite possibly - my housemates J reg Polo takes about 100 miles of ranged driving before the ECU settles into the right groove. Not sure how old your engine is, and obviously the ECU is probably going to be a bit more complicated that an old Polo...but there is surely to be some ECU learning time on it.

 

I dunno - it's an old engine ('85/'86) and the ECU won't be that clever.

I asked the question over on the Kit Car forums, and the chaps there reckon 10 mins of idling and a short drive gets the ECU and the engine re-aquatinted again.

 

To be fair a J-reg polo might have a pretty ancient engine in it, especially if the 325's was newish at the time...

*edit* A 1992 polo had a refresh in 1990, but I can't find if the engines were updated much or not. Moot point anyway.

Either way it might sort itself out, or just be one of those gremlins you never cure!

 

I'm going to let it idle for some time later on, and see what that does.

I may also replace the intake boot and ICV hoses just in case, as they are the originals - and whilst I can't see any splits, the main boot does look a little brittle inside - maybe it's leaking a little and causing unmetered air to get into the engine.