Mi16 Missfire After 40 Mins..really Annoying Me!

[jonathan205 0]

Hey guys,

 

I recently bought a 205 with mi16 engine..

 

its starting to really wind me up now as I keep getting a random missfire. It only occurs after around 40 mins of driving.. if the journey is less than 40 mins its 100% perfect!?

 

I presume therefore it has something to do with temperature?

 

When the missfire does occur, between 1k and 3.5k revs is pretty un drivable and jerks around all over the place and cuts out, but above 3.5k it seems normal!..very confusing :s

 

I have anew set of plugs and leads on there and have cleaned the dizzy cap up really well..the only thing i havent replaced is the coil.

 

Any helps would be excellent as im running out of patients with it!!

 

Cheers,

 

Jonathan

[hexhamstu 9]

Have you swapped the ignition amp? I'd try that and the coil as the first port of call. When it misfires does the rev counter jump up and down wildly?

[Daviewonder 533 3 Cars]

My 1.9 8v used to do this, I couldn't work it out as it was always when I went to pick things up that I'd bought on line. It turned out to be the ignition module breaking down when it got hot but it never got hot enough on normal day to day use

[Simes 248 2 Cars]

Check inside the distributor cap, is the carbon bit in the centre still there unbroken?

[j_turnell 134 3 Cars]

Make sure the ign amp has some heat proof paste behind it as this could be the problem.

[jonathan205 0]

Whats an ignition amp!? I checked the dizzy cap and it was a little dirty but nothing major, i cleaned it up and has made no difference.. It does sound like the coil tbh, but ive never heard of this ignition amp so best check that as well! The rev counter doesnt jump around no..

[jonathan205 0]

oh and where is the ignition amp too please!?

[Simes 248 2 Cars]

Normally attached to a small piece of aluminium on the inner wing between the battery and the expansion tank or on the opposite side near to the fuel filter.

 

Looks like this

 

[Veero 1]

Another vote for ignition amp. Failure modes vary. Mine would run fine, get hot and just cut dead and then would refuse to restart until cooled again. Putting in a known good used amp changed everything and it's been fine now for 6 months. Be wary of aftermarket amps, Intermotor in particular.

Edited June 22, 2010 by Veero

[C_W 3 1 Cars]

Change the rotor arm IMO - even if it looks new!

[24seven 104]

Another vote for the ignition amp. Seen a couple of Mi16's and an 8v all suffer randomly because of these.

[jonathan205 0]

cool, where would i find a good ignition amp to replace it with then?

[TheLarneMan 4]

Change the rotor arm IMO - even if it looks new!

 

I'll second that.

[jonathan205 0]

right I shall buy a new rotor arm and ignition module. It was mention previously to avoid cheap makes..

 

can someone give me a quick list of the makes to avoid and the best ones to get?? Im guessing bosch is the one to aim for if possible?

 

thanks

[jonathan205 0]

http://cgi.ebay.co.uk/Electronic-Ignition-...=item335801d0ef

 

this one any good?

[Simes 248 2 Cars]

Right!

 

Change your rotor arm first.

 

The ignition amp you need its a Bosch one (like in my photo), any other make will cause an issue.

However I forked out £50 on a Bosch one and found it limited my revs and missfired badly. There was a complete thread all about this years ago by me.

 

Useful thread

 

The best course of action is to get a known working second hand one, I do believe Miles may be able to helpo you with this.

 

 

Here is a list of threads that could also help you.

 

Misfire threads

[jonathan205 0]

thanks for these mate, very useful! quick question you may be able to help with..does the amp have to be bolted to somethin metal as an earth? I was thinking of re locating it further down the front away from the engine??

 

and also, where does the paste go!?

[Simes 248 2 Cars]

Ok, the amp is normally bolted to a piece of aluminium which in turn acts as a large heatsink. This is screwed to the inner wing but is insulated from it. If your ignition amp is not attached to anyhthing then that will be the problem. The thermal paste is applied to the ignition amp to aid heat conduction to the aluminium.

[jonathan205 0]

right im with you, im wondering if it will be a good idea to re locate the amp and the aluminium down to near the headlight area as its an inch away from the hot engine at the moment!

[welshpug 1,631]

should be fine if you don't use your lights never had an issue with the placement of them soaking heat up, only the dissipation of heat.

[Simes 248 2 Cars]

right im with you, im wondering if it will be a good idea to re locate the amp and the aluminium down to near the headlight area as its an inch away from the hot engine at the moment!

 

No need.

Some cars it's on the inner wing close to the battery on later ones it's next to the master cyclinder, the aluminimum is about 5mm thick.

I did have some spare but I've just used it up for something else.

[24seven 104]

When I rewired the engine on my 205 in February I found there are a couple of threaded holes on the side of the air flow metre which worked perfectly for attaching the ignition amp to. Previously it had been at the back of the engine bay above the gear rods and proved not to be the cause of any of the problems I was having at the time. The ally backing they're thermal pasted/screwed to works really well.