Hey guys, i hate making threads like this but have searched and found no answer and this issue is killing me... The car starts fine, idle is high but smooth as (always has been), drives perfectly smooth but if you put the motor under any load it misfires, backfires and chokes... come back off the throttle it drives smooth again. to give you an idea of the power loss, it's manual and on wet roads I cannot spin the tyres, even with the clutch, but if i putt around like a grandma it runs perfect. I have changed plugs, cleaned injectors, there are no air leaks, dizz cap is clean, leads are new, CAS has been changed recently, afm has been tested fine, fuel reg is working, fuel pumps are working (blocking return line causes it to overfuel and stall) and timing is sitting on a 25"advance. i am seriously stumped, please help this is driving me mad.

Quote: Originally Posted by VL 88 WA Hey guys, i hate making threads like this but have searched and found no answer and this issue is killing me... The car starts fine, idle is high but smooth as (always has been), drives perfectly smooth but if you put the motor under any load it misfires, backfires and chokes... come back off the throttle it drives smooth again. to give you an idea of the power loss, it's manual and on wet roads I cannot spin the tyres, even with the clutch, but if i putt around like a grandma it runs perfect. I have changed plugs, cleaned injectors, there are no air leaks, dizz cap is clean, leads are new, CAS has been changed recently, afm has been tested fine, fuel reg is working, fuel pumps are working (blocking return line causes it to overfuel and stall) and timing is sitting on a 25"advance. i am seriously stumped, please help this is driving me mad. What did the ECU test tell you?

check coil

havent tested ECU, how do i test coil>? i've checked leads and the spark seems strong.

I tested Leads on mine and all were within spec according to Gregorys Manual (Lessthan 22000 ohms) and it was missin an fartn under load. I bought new leads which were approx 5000 ohms and it fixed it. As soon as you put it under load it makes it harder for the spark to jump the gap and it takes the easiest rout straight to head (earth). Hope this helps

hrmmm, ok thanks guys. the leads are blue top-gun's and were replaced when i did the motor, so i'll throw a new coil on first and see if that sorts it.

iv got the same problem here and iv did all that my vl still runs like kak everything in the vl engine bay is full on new but if i push it ova 3 rph it starts choking and i hav to drive it slow

Try another CAS/Dizzy and see how you go....

could be running lean due to fuel blockage, fuel reg, or fuel pump, AFM could be gone, or you could have problems with the elctrical connections on the coil or dizzy and everytime you give it load the engine moves a bit, screwing around with the connections, thats what got me Some original photos have not been recovered yet.

my valve stem seals were ****ed and it caused a very similar problem to this although mine would choke so bad that it would sometimes stall keep it in mind if all else fails

Or it could be your fuel pressure regulator. What colour are your plugs after trying to drive it under load?

Steve: When i take out the plugs they look good but have a fair bit of carbon on the electrodes, particularly 3 and 4. thanks for all the feedack guys. did the coil today, all the wiring and plugs in the bay are new, as are almost all of the sensors on the motor so i'm pretty sure the spark side of things is fine now. changed the oxygen sensor as well, then checked the timing and replaced/adjusted the TPS and the issue is still there. It drives like new as long as i dont try to go up any steep driveways or overtake anybody... as soon as i accelerate heavily i lose all power and it starts literally spitting flames out the exhaust... I dont think it's due to the engine moving and shaking wire connections because if i am cruising along in a set gear at a set speed (it's a manual) and i start to go up a hill it will start to choke about halfway up just from the extra load of the hill. Fuel filter is fine and i'm putting on a new regulator tomorrow but failing that i am really stumped. any more ideas would be greatly appreciated Some original photos have not been recovered yet.

But did you try swapping the dizzy for another one Some original photos have not been recovered yet.

ok i have now tried another dizzy, No love. checked every hose for vacum leak, checked injectors individually, replaced oxy sensor, tps, afm, plugs and coil. The timing belt is new and timing is not advanced or retarded at the belt. i hooked a timing light to it yesterday and matched up the marks on the crank. in order to make it actually driveable the timing is now advanced like 45" at the dizzy (this is wayyy wrong but for some reason it's the only place it will run (I checked very carefully b4 driving it and its not pinging) still backfiring and missing under load. any more ideas?!?! i've blown like $800 on this now and the car still wont run right Some original photos have not been recovered yet.

Quote: Originally Posted by VL 88 WA ok i have now tried another dizzy, No love. checked every hose for vacum leak, checked injectors individually, replaced oxy sensor, tps, afm, plugs and coil. The timing belt is new and timing is not advanced or retarded at the belt. i hooked a timing light to it yesterday and matched up the marks on the crank. in order to make it actually driveable the timing is now advanced like 45" at the dizzy (this is wayyy wrong but for some reason it's the only place it will run (I checked very carefully b4 driving it and its not pinging) still backfiring and missing under load. any more ideas?!?! i've blown like $800 on this now and the car still wont run right This prob just started 1 day or was it after some major changes/work?? You still haven't done a ecu test for error codes yet OR swap the ecu with another You did your dizzy timing when the car was hot? if not it's wrong.. Some original photos have not been recovered yet.

started one day bu thas gotten worse did ecu test and swapped as well timing, tps etc. were all adjusted with engine running and hot. i'm running out of ideas here... this is gonna turn out to be some insignificant $5 part and it's gonna cost me a fekkin grand to find out Some original photos have not been recovered yet.

Quote: Originally Posted by VL 88 WA started one day bu thas gotten worse did ecu test and swapped as well timing, tps etc. were all adjusted with engine running and hot. i'm running out of ideas here... this is gonna turn out to be some insignificant $5 part and it's gonna cost me a fekkin grand to find out Have you had the fuel pressure checked to rule out pumps and FPR.. Some original photos have not been recovered yet.

I bet in hindsight you wish you had spent $200 for dyno time to help diagnose the problem. Unless you've got access to parts to substitute, dyno time is the quickest (and sometimes cheapest) way to go. A high idle usually indicates an air leak after the throttle body. Maybe an inlet manifold gasket?

Quote: Originally Posted by MonstaS4 I bet in hindsight you wish you had spent $200 for dyno time to help diagnose the problem. Unless you've got access to parts to substitute, dyno time is the quickest (and sometimes cheapest) way to go. A high idle usually indicates an air leak after the throttle body. Maybe an inlet manifold gasket? yeah your right, wish i'd gone for a dyno. the idle has been high for aaages, it's to do with the idle control valve thing on the back of the plenum, regardless of that the motor has always run mint. For a non-turbo it's got very respectable power so i'm not concerned by the idle thing. just the rest lol

a high idle can also be the Air regulator unit which raises idle when the car is cold, as it heats up the window closes and no air gets threw so idle drops, these often fill up with carbon/slug and can get stuck