Mi16 running problems

THE ENGINE: PSA's XU9J4 (Mi16) Running Motronic ML4.1.

THE PROBLEM: A few nights ago I made a short journey into town. The engine started and drove fine for 5 minutes and then midway through warming up it started missing badly for a few minutes and then it completely died! So, I restarted her. And it was ok.... The next day I was a bit I miffed. But I found the TPS connector to be loose and thought it might be that. Alas I did the same journey tonight and the problem happened in exactly the same time and way as a few nights ago!

A bit of background...

Engine has always had a starting problem. Starts fine when stone cold. Starts fine if it was switched off and restarted within about five minutes. But after that approx. 5 minutes and say 12 hours it will turn over for 5-10 seconds before reluctantly starting.

Also... If I'm drifting along in traffic at say 2000rpm in 2nd gear with foot off gas pedal and then I go to accelerate the car will jerk a few times before smoothing out. And when taking foot off accelerator it jerks again as if the fuel cut off wasn't immediate...

I'm thinking all these are related. And it seems like whatever is playing up is not liking certain temperatures.

I know it's very hard to diagnose this without you actually testing the engine yourselves but just maybe the likely cause of this will stand out to one of you.

Thanks Kris

Reply to
Kris
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temp problems are usually either coolant sensor or crank sensor OR (sometimes) just the connections

Reply to
Mrcheerful

I just pulled all the HT leads off and stuck some spare spark plugs into them and tried to start the engine. Did I get sparks? Yes - BUT each plug sparked in firing order as if the engine was turning over about 20rpm! What does that indicate? (when the starters turning engine over it's doing over 100rpm isn't it?)

Reply to
Kris

no they don't spin very fast, you can see each spark

Reply to
Mrcheerful

...it's a 4 stroke engine. Each cylinder will only fire once every two revolutions of the engine.

Reply to
Conor

not always, many engines fire every stroke nowadays (wasted spark double coil, like mondeos, fiestas etc.) I don't know the OP setup, but it is probably the same as mondeo etc.

Reply to
Mrcheerful

Well yes 1 spark per cylinder every 2 crank rotations.

I found out that the starter motor should turn over the engine at

165rpm. That works out at an average of 2.75 sparks a second. There was alot less than that! It was litterally like one plug would spark, wait 2 seconds, another plug would spark, wait 2 seconds, another plug would spark.... and so on. What I want to know is WTF could cause this.

Very frustrating lol

Reply to
Kris

Still arsing about gathering parts to try but I would just like to add:

Kangeroo'd again today once it got up to temperature. Very violently like I'm jumping on and off throttle. But as soon as I put foot to floor it stopped.

This is very intermittant in nature - must have been a week ago it last happened.

Runs ok on wide open throttle - what does that tell anyone?? (That I should drive like a maniac everywhere?)

Reply to
Kris

Throttle pot needs cleaning/replacing?

Reply to
PC Paul

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