92 replies to this topic

[BoyracerAU]

Hmmm, sounds like we might be on to something here.

I haven't been able to use this car hardly at all seeing as it's been having dramas, so I could be wrong, but then I'm fairly certain I have never seen the temp gauge go above the halfway mark. I'm very tuned into keeping an eye on gauges as I'm no stranger to old cars.

I'll check this out tonight.

Thanks Sprocket for the heads up.

[BoyracerAU]

Well, this is bizaare!

The last thing I'd done was put octane booster/injector cleaner in with the fuel.

The Mini hasn't been started since the weekend, but I took it out for a run tonight. A combination of suburban driving and a few short bursts in 90km/h zones. I had it in mind to keep an eye on the temp gauge and an ear out for the leccy fan.

The temp gauge went up to a smidge under halfway. It took 20mins to get there. It occasionally dropped a couple of millimeters below, but stayed a smidge under halfway 99% of the time.

It never went over the halfway mark. And I didn't hear the leccy fan kick in at all, not to say that it didn't, I guess. But if it did, I certainly didn't hear it come on.

I drove for a full hour and ten minutes before the popping and misfires kicked in at around the 2,200rpm mark. Yup! My old friend was back.

Now here's something. This only started happening after I'd gone over (dropped savagely into?) a pretty severe pot hole. The suspension is very hard so the car certainly took a good knocking.

Until this, I'd actually begun to think the injector cleaner (of all things!) had done the trick.

Bugger!

[ICAM]

Well, this is bizaare!

The last thing I'd done was put octane booster/injector cleaner in with the fuel.

The Mini hasn't been started since the weekend, but I took it out for a run tonight. A combination of suburban driving and a few short bursts in 90km/h zones. I had it in mind to keep an eye on the temp gauge and an ear out for the leccy fan.

The temp gauge went up to a smidge under halfway. It took 20mins to get there. It occasionally dropped a couple of millimeters below, but stayed a smidge under halfway 99% of the time.

It never went over the halfway mark. And I didn't hear the leccy fan kick in at all, not to say that it didn't, I guess. But if it did, I certainly didn't hear it come on.

I drove for a full hour and ten minutes before the popping and misfires kicked in at around the 2,200rpm mark. Yup! My old friend was back.

Now here's something. This only started happening after I'd gone over (dropped savagely into?) a pretty severe pot hole. The suspension is very hard so the car certainly took a good knocking.

Until this, I'd actually begun to think the injector cleaner (of all things!) had done the trick.

Bugger!

That is why I wanted you to clean the injector first. There is a strainer at the injector body that might be clogged. If I got time I shall take picture on how to open the injector this weekend.

[Sprocket]

If the injector is clogged or dirty it will be all the time and the problem would be evident all the time. This is not a fueling issue. It is something to do with the wiring and control of the relay pack. Power is being dropped from the coil, causing the tacho to bounce. This is either the relay pack dropping the main power, or there is a broken/ loose wire in that circuit.

A bumpy ride can cause the inertia switch to jump around, and if its slightly dodgey, can cause missfire due to the fuel pump cuting in and out. I cant see this causing the tacho to bounce, as there is still power to the coil and a spark will still take place. eliminate the inertia switch for now by linking it out, just dont crash into anything while its linked out. This happened to a friends SPi, intermitant missfire, (not what you describe) and we diagnosed it as the inertia switch, fitted a new one and the problem dissapeared. I have looked at a few SPi's now with a wiring fault on the fuel pump power supply wiring, in different places, but it was the same symptoms, either the engine wouldnt start, or it was an intermitant missfire.

Have you replaced the relay pack yet, have you taken the top off it and had a look inside yet, have you cheacked the relay pack plug terminals behind the white pull out protector?

I would be temptd to start using instruments to measure voltage of various components and go for a drive and see what is actualy happening.

[BoyracerAU]

Hi Sprocket,

Thanks for all that.

Despite having read about it so many times, can you believe I forgot about the inertia switch last night! I'll check it out and the wiring over the weekend.

Yes, I've swapped relay packs and had both the old and the new packs open and looked inside. All clean. No signs of burning within or at the plugs. Hardly any dirt to speak of either!

I agree, it does look like it's down to measuring volts here and there. I wish I'd done it last night when the car was actually playing up, but it got quite late and that hotdog on the back would've had half the neighbourhood up in arms.

[ICAM]

"Manx Mini....

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Hi.

I have a similar problem with a 1996 SPI cooper. Initially purchased as a non runner. It had been running but broke down on a test drive. (We knocked the price down) could not find much wrong but it would only turn over and not fire up. Changed the ECU, nothing. Changed the ECU and engine harness from a running 1992 SPI and it started, but then stopped. Changed the fuel tank and it runs, (faulty fuel pump) but will not go above 2500 rpm. Just changed the fuel filter, reset the stepper motor and the fuel cut off switch and turned the key. It started, ran smoothly and revved past 2500 rpm. Perfect! When we came to start the mini later on it had reverted to the 2500rpm limit. Changed a vac pipe as one was split but to no avail. I have previously changed the coolant temp sensor (it wasn't a new one but it had been ok in the other mini it came from) in the bottom of the inlet manifold and the pre heater element in the manifold (The manifold heater connection had melted, any reason why?) The mini splutters and pops if you try to rev it above 2500rpm. " quoted from page 3 , spi problem.

I think that this fellow prob is similar to yours. He change the throttle/ stepper motor assy and solve the problem.

Maybe you can refer back to Sprocket post on how to check the stepper motor accordingly.

[BoyracerAU]

Hi ICAM,

Thanks for that. I've actually been in correspondence by private message with a few people whose problems sounded a bit like mine. Manx was one of them.

Unfortunately, he replied that he never did sort it out. He ended up changing cars!

[BoyracerAU]

I didn't have time to post this earlier as I was at work. Don't you hate it when work interrupts more vital things like writing posts on Mini forums???

Anyway, this weekend one of Sprocket's earlier suggestions finally penetrated my grey matter. He'd suggested I open the multi plugs that go into the Relay Pack to see how the little connectors were doing on the inside. Hitherto, I'd ready that as merely taking the plug off the Relay Pack which I'd done.

So this weekend, I took the plastic covers off from within both the multiplugs on the Relay Pack as well as the one on the Inertia Switch and gave these a bit of a look. I also checked the wiring to the Oxygen Sensor and the Throttle Position Sensor. Everything looked fine. No sign of burning or anything weird. I wasn't sure how to see further in, so I didn't try to open anything up further.

So Sunday evening I took the Mini up the road to get a pizza. The interesting thing is that the drama actually happened before the temp gauge reached operating temperature! This is the first time this has happened and the car wasn't at operating temperature.

Coincidentally, the drama kicked in as I was whipping through a left hand corner. I say coincidentally as I was going whipping through a left hand corner when it kicked in last time, albeit after one hour and ten minutes of running on that occasion.

So, it looks like I'm looking at a dodgey wire or connection in one of these plugs.

[ICAM]

Have you tried going long uphill. This is my method to check for the fuel pump capability. If let say the car stall or jerking halfway, means that you are having problem with the pump.

[BoyracerAU]

As it happens, my driveway runs for about 150m and it's all uphill, about a 45 degree incline so it's not the fuel pump I guess then.

I'm going to replace the oxygen sensor and re-check all those connectors this weekend. I thought I'd get the car warmed up, get the air filter off and try wriggling all the connectors whilst the engine's running. Hopefully, this will help me locate where the problem is.

Edited by BoyracerAU, 27 February 2008 - 12:33 AM.

[BoyracerAU]

Well I hope no one other than me has been holding their breath for this one.

Hot on the heels in Paul's wake, I'm happy to report that my car is also now sorted!

It was the Crank Position sensor. According to the Mini specialist I used this time (Mini Classic - Greig Malaure) , the sensor looked fine and tested okay, but somehow had an intermittent fault. A new CAS has now been fitted and the car has done 200kms since it last misfired. I picked it up tonight and it didn't miss a beat.

The CAS had actually been checked by the local mechanic who had the car for a couple of weeks. This was his first guess. He'd checked it and found it to be okay.... but it wasn't, so bit of a bum steer there. I'd also tried wiggling the cables that go to the CAS and failed to replicate the problem so the CAS got a tick that it really shouldn't have.

To save people from reading over the last six pages, the original problem was that the car all of a sudden developed an intermittent misfire when it was warmed up and only when I tried to rev above 2,000rpm. The revs would plummet to idle speed (850rpm) whether I was accelerating or cruising. There was no real rhyme or rhythm to it except that it never happened when the car was cold. It only ever happened when the engine was at operating temperature. I was able to rev up to about 2,000rpm, but the moment it went over, it would pop and fart and the revs would drop back to idle speed. On one occasion only, did the engine actually cut out on me. Apparently, it also did this for Greig.

The installation of the alarm on the same day of the first misfire didn't wasn't helpful. It completely threw me off the track. It obviously had nothing to do with the problem. Just a coincidence!

Anyway, I've just washed it and put it in the garage. It's taking me to work for the first time tomorrow.

Edited by BoyracerAU, 02 April 2008 - 03:40 AM.

[Sprocket]

Well Well, really glad you found the problem. Intermitant faukts are the worst kind as its never faulty when you test things.

Steep learning curve for us all. Good info obtained

[ICAM]

Bravo, at last everything solve. I'm happy to hear that also.

[BoyracerAU]

Thanks guys. I'm very grateful for all the help and advice, particularly Sprocket's, but of course everybody who chimed in with suggestions and descriptions.

Until now, I had no knowledge of EFI and I hadn't spent much time playing under the bonnet, so it really was time I learnt something!

[mogg]

Congrats, I thought you may have been putting in a carb.