Mi16 Hesitating At Around 3.5k - 4.5k

[trialster 0]

hey guys, just finished my mi16 conversion in my 309, but now i have problems!

 

when i accelerate in any gear (the more load the worse the problem) between 3.5 and 4.5k the engine hesitates and stutters before reaching 4.5k - 5k, at which point it really pick up smoothly (and quickly ! )

 

between idle and 3.5 k it seems fine. it also feels fine above 5k (although haven't been too far through the rev range.)

 

this is really bugging me! any help will be muchly appreciated

 

Will

[welshpug 1,626]

does it happen on Wide open throttle and part throttle?

[trialster 0]

does it happen on Wide open throttle and part throttle?

 

definitely at part throttle.

 

haven't tried doing it with full throttle as it simply feels like it'll make it worse!

[DRTDVL 4 1 Cars]

my s16 did that when the plug where shot... i replaced the plugs and it was fine...

 

don't ask me why... it just worked.

[hexhamstu 9]

ignition amp?

[trialster 0]

hmm i dont think it'll be either of these tbh!

 

the plugs are new

 

the ignition amp was working when the engine was in the 405.

 

its a tricky one, the only thing i can think of that's different is one of the HT leads... i'll fit new HT leads when they arrive and see if this rectifies things...

[pete1986 2]

I had this problem on my mi16 recently, misfired at exactly the same rev range as you described. New plugs, ignition amp and cleaning up earths solved it.

[munster 0]

Igniton amp solved my similar problem.

[trialster 0]

ok then, if these new leads dont work, i'll remove and clean my earth cable and plugs. then if that doesn't work then i'll start looking for an ignition amp!

 

cheers for the help so far!

[trialster 0]

found loads of oil on all my plugs :s

 

thing oil is getting in through the inlet somewhere ? :S

[dcc 855]

did you rebuild the head? or take off the rocker cover?

 

If you have, make sure you reseated the rubber rings, 4 of them, one for each spark plug. sits on the top of the head, between the rocker cover and the metal of the head. without these, i wouldnt have thought they wouldnt be there, but best to check.

[trialster 0]

yeah they're in there. i took the rocker off to paint it. i replaced the rocker gasket but it didnt come with these O rings

 

any other siggestions? could oil be coming in through the inlet somehow?

[24seven 104]

check the coil. I had weird running issues with mine on the coil that came with the engine. swapped it for the coil off the 1.6 engine and cleared it up mostly. it still occasionally refuses to go above 4-5k even in neutral, which I suspect is the dodgy ignition amp that was dodgy even before the swap.

[luggy 13]

when i accelerate in any gear (the more load the worse the problem) between 3.5 and 4.5k the engine hesitates and stutters before reaching 4.5k - 5k, at which point it really pick up smoothly (and quickly ! )

 

between idle and 3.5 k it seems fine. it also feels fine above 5k (although haven't been too far through the rev range.)

 

Tried a known good AFM? Im led to believe that above 5k the AFM no longer meters air/fuel

[trialster 0]

Tried a known good AFM? Im led to believe that above 5k the AFM no longer meters air/fuel

ahh right, that'd make alot of sence! i shall ask a mate if i can try his, if not then i'll get some electrical cleaner in there and see what happens. it's still strange how the 405 (donor car) ran really well on the 160 mile drive home!

[luggy 13]

ahh right, that'd make alot of sence! i shall ask a mate if i can try his, if not then i'll get some electrical cleaner in there and see what happens. it's still strange how the 405 (donor car) ran really well on the 160 mile drive home!

 

Had a similar experience with my donor after eventually getting it started after finding out it was a knackered ecu , replaced plugs (new), leads, dizzy, rotor arm, coil, crank sensor, ignition amp. After the rebuild it would only run on 2 cylinders, turns out 2 of the spark plugs was fecked and the throttle body was causing high idle issues which was replaced with a VAG item. I do like a challenge but a least with the 8v there was some continuity with the faults and troubleshooting

[trialster 0]

so you mean my ecu may be knackered? or my spark plugs or what? not being rude but i can't seem to follow your post :S

[luggy 13]

so you mean my ecu may be knackered? or my spark plugs or what? not being rude but i can't seem to follow your post :S

 

I was just empathising the fact you had a donor car which runs fine, transfer to another car suddenly you have certain components playing up.

Edited January 20, 2009 by luggy

[trialster 0]

righteo no worries, didn't know where you were initially going with that

 

cheers for the help, i'll wack new leads on and clean some more components and see if it makes any difference!

 

Will

[Tom Fenton 1,526]

Faulty (new) igntion amp gave me very very similar symptoms to the one you describe. Power up to 3500rpm, big misfire and jerking till 4500rpm, then cleared up and ran round to the limiter like a good'un.

[S@m 156]

I had the same problem of not being able to rev past about 3.5k at all, like a rev limiter cutting in and it turned out to be the ignition amp. Im not sure if it would be the AFM because by about 4k its fully open and so doesnt have much more to do (apart from restrict the intake!).

Sam

[trialster 0]

ok guys, looks like the ignition amp is at fault then!

 

is there anything i can do to fix it? warm it up to get rid of any condensation? spray it with any form of cleaner? soak it? hit it with a hammer ?

[S@m 156]

Well, you could clean up the contact at the back and make sure it was some fresh thermal transfer paste on there. Aside from that, maybe spray some water dispersant on it and its connectors, but im afraid that if its buggered, its buggered. Worth a shot though!

[trialster 0]

ok cheers fella's this problem is now sorted! for everyones info it turned out to be the ignition amp. a mate (24seven) has lent me his untill i can come up with a replacement for him

 

ta for your help!

 

Will