145 replies to this topic

[JimCooper]

A couple of years ago the old engine popped and I had an MG metro engine dropped in, I read in this thread that the spi system doesn't respond well to the MG metro cam would this explain my lumpy idle and overfuelling? The other thing I have done is fit a single box centre exit system and a de-cat as the cat collapsed.

The MG cam is most definately your problem. Due to the overfueling the cat has been overheating in load conditions resulting in its failure. Theres just too much overlap on the MG cam to give a nice smooth MAP signal.

Swap the cam out for a Kent 274 and fit another cat and you should pass emissions no trouble as long as there is no other faults. Best get the valve seats recut as this can affect it as well

Thanks for the advice, the cat collapsed when the standard engine was in but yeah it would have had that effect with the MG engine fitted.
Is the cam change a big job? If this and a cat cures my probs i'll be v. happy

[Sprocket]

Cam change usualy means an engine out job unfortunately. You dont have to pull the engine entirely apart though.

[cmice]

I have found that the relay for the heating element of the sensor can fail. This produces a Lean missfire at idle, yet all other driving conditions are fine. The reason for this is, at idle the sensor is not running hot enough and relys on the heater to keep it at operating temperature. The sensor reads constantly high voltage and the ECU thereby leans off the fueling. To test if this relay is faulty, the easiest thing to do is swap it with the electric fan relay next to it and see if the missfire dissapears.

I'll echo the sentiments of another poster that the missing pictures make this info hard to follow. It is *extremely* valuable, however...so please don't consider this a complaint...perhaps just a nudge to fix the pictures.

Regarding the relay, can you indicate exactly which one is the relay? The diagram shown on minimania is somewhat helpful, but the pictures of the relays themselves cannot be correlated to their function shown to the right since the numbering doesn't align.

http://www.minimania...es/90_2_J14.htm

Any hints?
Thanks!
Chris

[Sprocket]

I'll get it sorted soon, unfortunately I am now megga busy getting the Mini ready for The British Mini Showdown.

However, the Lambda (oxygen) sensor heater relay is located on a bracket on the right hand side of the bulkhead as you stand at the front of the car, looking at the engine. Its a yellow siemens job. There are two in this area, from left to right, Lambda heater relay, electric fan relay, and then the black thing to the right of those is the fuel cut of inertia switch.

Hope that helps a bit.

[cmice]

Still having trouble diagnosing my issue, so will try to post details and see if sounds familiar. Is '94 spi Mini, 1275cc.

Starts perfectly from cold, will warm up nicely. Runs great everywhere, from idle to highway speed (70mph+). In short, it runs great. Here's where the fun starts...

Arrive safely at your destination, say a grocery store. Go inside, do your business, come back out and get in. Say all of 10-15mins have passed.

Start the car, and it starts just fine...settles to a somewhat high idle, then drops to normal in a few seconds.

As you select a gear, and begin to pull away...as the throttle just comes off idle, the rpms will drop drastically...and the engine will go into this high-low hunting pattern...alternating from very rich (puff of black from the tailpipe) to very lean.

If you needle the throttle pedal, you will be able to get the revs above ~1500rpm (don't have a tach, so is a guess)...at which point it runs fine. Keep it there for about 1-2 minutes (ie. driving off) and the condition goes away entirely.

I've done the following so far:

1) checked and gapped plugs, they look good (cap, rotor, leads are less than 1.5yrs old)
2) checked air temp and coolant temp sensors
3) replaced ignition coil with pertronix unit
4) used compressed air to blow a shocking amount of fluid out of the map sensor fuel trap
5) checked and tightened all connections and hoses

The oxy sensor is relatively new, but could be suspect as it's had other problems over the past year which could have contaminated the sensor. Could also be throttle pos sensor going bad? These clean-able? Any other ideas?

Chris

[cmice]

The oxy sensor is relatively new, but could be suspect as it's had other problems over the past year which could have contaminated the sensor. Could also be throttle pos sensor going bad? These clean-able? Any other ideas?

I replaced the oxygen sensor, with no change in behavior. The next easiest step was to swap the ECU with an unused remanufactured unit I had on shelf (just a stroke of luck that I had one). So far, the problem appears to be resolved. This would indicate the MAP sensor in the unit is failing...or clogged...or? Anyway, will update if this thread if it hasn't resolved the issue.

Wondering if anyone has worked out how to replace the MAP sensor in these units? There has to be a common-part sensor that this one was "borrowed" from.

UPDATE: We are now convinced that this has fixed the aforementioned problem, and made a marked improvement in fuel consumption (approaching 40mpg US).

Chris

Edited by cmice, 28 July 2007 - 05:08 AM.

[minitartar]

as any body changed an spi back to carbs ?

[Sprocket]

as any body changed an spi back to carbs ?

You wont find it here

[Sprocket]

Be aware that the super cool two core Rad with the 'screw' in thermostatic switch for the electric fan, the operating temperature of the switch is low, resulting in over cooling causing open loop control and rich running.

[miniproblems]

Hi! I have a Mini 93 SPI. I have read your post with great interest, but have a few questions.

It all started with the car not starting. Since then i have changed fuel filter, fuel pump, vacuum hose from ECU and the red vacuum hose.

The mini starts up nicely now, BUT if I press the pedal rough it makes popcorn noises somewhere under the bonnet, and it all sounds unstable from the engine. I have made a video of me starting up an pressing the throttle. Please help med fix this problem! I have little mechanic experience.



Thanks for your help!

[cmice]

Hi! I have a Mini 93 SPI. I have read your post with great interest, but have a few questions.

It all started with the car not starting. Since then i have changed fuel filter, fuel pump, vacuum hose from ECU and the red vacuum hose.

The mini starts up nicely now, BUT if I press the pedal rough it makes popcorn noises somewhere under the bonnet, and it all sounds unstable from the engine.

Sounds to me like ignition timing. Those pops could be mis-timed sparks causing premature ignition of the intake charge (while the inlet valve is still open). Ignition timing is all electronically controlled by the ecu based on the crank angle sensor. But let's not assume there's something wrong there yet. Make sure your cap, rotor, wires are in good condition....also if you took the plug wires off at any point in your previous work, make sure the wires went back to the correct plugs.

Chris

[miniproblems]

Hi! I have a Mini 93 SPI. I have read your post with great interest, but have a few questions.

It all started with the car not starting. Since then i have changed fuel filter, fuel pump, vacuum hose from ECU and the red vacuum hose.

The mini starts up nicely now, BUT if I press the pedal rough it makes popcorn noises somewhere under the bonnet, and it all sounds unstable from the engine.

Sounds to me like ignition timing. Those pops could be mis-timed sparks causing premature ignition of the intake charge (while the inlet valve is still open). Ignition timing is all electronically controlled by the ecu based on the crank angle sensor. But let's not assume there's something wrong there yet. Make sure your cap, rotor, wires are in good condition....also if you took the plug wires off at any point in your previous work, make sure the wires went back to the correct plugs.

Chris

Ok, i couldnt find something wrong with the distributor cap and the wires and spark plugs should be in good condition. When I changed the spark plugs I remowed the leads one at a time. It doesn't sound very mechanic, more electrical/injection problem (I could be wrong). The car can sometimes just die in idle and when driving; if I press the peddle hard its like it doesn't get fuel and suddenly get some, and doesn't again. Maybe it needs more fuel? It's difficult to describe for a non-mechanic person...

Thanks

[cmice]

Ok, i couldnt find something wrong with the distributor cap and the wires and spark plugs should be in good condition. When I changed the spark plugs I remowed the leads one at a time. It doesn't sound very mechanic, more electrical/injection problem (I could be wrong). The car can sometimes just die in idle and when driving; if I press the peddle hard its like it doesn't get fuel and suddenly get some, and doesn't again. Maybe it needs more fuel? It's difficult to describe for a non-mechanic person...

Ignition timing and fuel delivery are both controlled by the ecu. You've replaced that (with a known good one?) and you've gone from not starting to barely running...which in my mind means the problem is related to the ecu but elsewhere in the system (ie. sensors or wiring). Would not be something mechanical (ie. failing fuel pump or who knows what).

If the ecu is getting proper signals, fuel delivery should not be a concern...the ecu itself is extremely accurate when it's running correctly. So don't try to "adjust" anything there...there's really nothing to adjust. You did blow out the vapor trap prior to putting the new ecu in, yes?

The popping is an important symptom. Can you tell if the pop is a mechanical pop (ie. a mechanical binding and breaking-free? like a throttle linkage?), an electrical pop (ie. ignition coil that's shorting out? or arcing inside the distributor?), or a combustion pop (ie. a backfire you can hear inside the aircleaner)?

To me, from only the video, it sounds like a backfire through the intake. With a clear ear inside the engine compartment (ie. have a friend rev it while you listen carefully), you should be able to locate it. A piece of hose up against your ear makes a handy stethescope for locating hard to find noises (just don't blow your eardrum out).

Unless your cam timing has changed (ie. a skipped chain or a lobe has fallen off), the only way backfires happen (that I know of) is incorrect ignition timing. It is not adjustable as it's driven by the ecu. Either the crank-angle-sensor has gone bad, connector(s) is dirty, the rotor is incorrectly installed on the distributor shaft, there's debris in the cap, or you've got cracked ignition wires allowing for cross-firing. Check and clean all connectors related to the fuel injection (ecu, throttle body, and grounds).

Also, can you reconstruct the timeline...when was it last running properly? how did it run before it stopped running? when it stopped running, did it do anything of interest...or did it run fine on sunday, and monday just wouldn't start?

Chris

[miniproblems]

Ok, i couldnt find something wrong with the distributor cap and the wires and spark plugs should be in good condition. When I changed the spark plugs I remowed the leads one at a time. It doesn't sound very mechanic, more electrical/injection problem (I could be wrong). The car can sometimes just die in idle and when driving; if I press the peddle hard its like it doesn't get fuel and suddenly get some, and doesn't again. Maybe it needs more fuel? It's difficult to describe for a non-mechanic person...

Ignition timing and fuel delivery are both controlled by the ecu. You've replaced that (with a known good one?) and you've gone from not starting to barely running...which in my mind means the problem is related to the ecu but elsewhere in the system (ie. sensors or wiring). Would not be something mechanical (ie. failing fuel pump or who knows what).

If the ecu is getting proper signals, fuel delivery should not be a concern...the ecu itself is extremely accurate when it's running correctly. So don't try to "adjust" anything there...there's really nothing to adjust. You did blow out the vapor trap prior to putting the new ecu in, yes?

The popping is an important symptom. Can you tell if the pop is a mechanical pop (ie. a mechanical binding and breaking-free? like a throttle linkage?), an electrical pop (ie. ignition coil that's shorting out? or arcing inside the distributor?), or a combustion pop (ie. a backfire you can hear inside the aircleaner)?

To me, from only the video, it sounds like a backfire through the intake. With a clear ear inside the engine compartment (ie. have a friend rev it while you listen carefully), you should be able to locate it. A piece of hose up against your ear makes a handy stethescope for locating hard to find noises (just don't blow your eardrum out).

Unless your cam timing has changed (ie. a skipped chain or a lobe has fallen off), the only way backfires happen (that I know of) is incorrect ignition timing. It is not adjustable as it's driven by the ecu. Either the crank-angle-sensor has gone bad, connector(s) is dirty, the rotor is incorrectly installed on the distributor shaft, there's debris in the cap, or you've got cracked ignition wires allowing for cross-firing. Check and clean all connectors related to the fuel injection (ecu, throttle body, and grounds).

Also, can you reconstruct the timeline...when was it last running properly? how did it run before it stopped running? when it stopped running, did it do anything of interest...or did it run fine on sunday, and monday just wouldn't start?

Chris

Hi! I took the ECU inside for some days, but that didn't help. The pop is clearly coming from the air filter or/and around the air filter area. I havent tried to change the ECU with another one.

Timeline: Started with a flat battery. Recharged the battery. Some days later it wouldn't start. The starter motor just went around not starting the car, but some times it started after some tries. The car was at this time perfectly fine to drive and i didnt have problems like i have now apart from having some pop noises once or twice. The problem started to grow. After some weeks the fuel pump stopped making the fuel pressure sound before starting. So, i got a new fuel filter and recently a new fuel pump. It now starts but it acts like on the video. The old problem was that it wouldnt start. The new problem appeared after fuel pump-change.

Thanks for your help.

[Sprocket]

Please please start your own topic with your problems, as this will just get lost where no one will look for it.

Ok with that done

With this car being a 1993, i would expect there to be a throttle pedal switch. And with the age, these switches are failing. Check that this switch is making and breaking, with a digital meter, as you operate the pedal. The switch stuck as if the pedal was not depressed will give these symptoms, and WILL melt the cat if you drive it!