Hi guys,

 

What do you reckon on this one, When driving if i put my car say in 3rd while going slow and put my foot down, it starts to build up power but as soon as my turbo gauge hits maximum boost it starts hesitating, popping, and backfiring.

 

It revs fine, then you can watch the turbo gauge build up to it hits the top of the standard gauge,(running 14psi have after market gauge too.)and as soon has it hits full boost the car plays up, But if i rev it normally say hold it in gear its fine, only does it when in a gear where your down low in the revs and try to build up power,

 

Hope that makes sense,

 

Any help appreciated, thank you.

the spark will always follow the easyist route to earth, i doubt there all knackered tbh you'd have to be pretty damn unlucky!!! if they dont arch when they're in place they're prob fine, any smoke on accelaration?

 

No smoke at all, if i boot the car its great smooth as silk, tickover is smoothest its ever been its just that backfire its making me think a break somewhere, shutting the coil off then when it gets its power back sparking but at the wrong time.

Keep ur head up matey, we have all been there and u will sort it........

 

I have been reading this thread from the start and have been in ur shoes many times matey......

 

Have you changed the ECU? Do u have a series II PTU? Does ur 300 idle well? Do u get black spots on the rear bumper?

 

Alz.

Hi again,

 

Put cambelt back together today and started her up still the same:angry:

 

so pulled the coils out one by one and put a plug in to see if i could see any arching out,

when end of plug is on the engine sparks as normal, but if i face plug in the air and put the plastic shaft bit near metal i do get slight arching but the problem is i can get all 6 coils to do it, either their all broke or its one of them and cause it dont do it all the time its getting hard to find.

 

So dont know where to go from here its either drive it until it gets worse that its easy to find or suffer it.

 

Would a coil make big gun shot type backfires, to me its like its got to be a trigger problem or a break somewhere making coil fire at the wrong time.

But why only when the revs come down from 2100rpm. and in higher gears when driving slow then trying to accelerate without going back gears.

 

Im lost and to be honest im getting sick of the car,

i re shelled it and painted it 3times, its had 3engines 3sets of turbos an auto box and this is the 2nd manual box. clutch after clutch, shocks bushes, you name it its had it and it still wont run right,

i am allways skint cause the car gets nearly every penny i earn spent on it, problem is its like a never ending story i have it painted and it looks great then the engine/turbos or something horrid will go then by the time i sort money out and fix it, it gets a few stone chips supermaket dents, and has im so fussy it needs painting again, in the last year and half i have spent 6000 on paint, could have bought a mint zed for that alone.

i just want it painted so it looks great and everything to run great for just one yr.

Then you see my mates one in london his had a few problems with auto boxes but other then that its never bloody broke.

 

Sorry for going on but gotta say it to someone misses will kill me if she hears me say it has its what she has been saying for years, and i keep saying to her once its done we will be able to drive and enjoy it, Please tell me if i am dreaming or could this actually one day happen,

 

Thank you.

 

take the PTU off and give the prongs another clean, when i accidental fitted a clapped out PTU instead of my working one, it idled fine but soon as you came to drive it, it sputtered and jumped and backfired like a bish.

 

when you checked the timing did you do so with a timing light? as mine had a strange misfire on idle when it was out.

id have thoght it would be missing all the time if there was a break not just under load, i guess it could be the coil pack itself have you tested how far the spark jumps from the spark plug thatll give you an idea of coil strength and have you checked the gapping on the plugs is right?

Keep ur head up matey, we have all been there and u will sort it........

 

I have been reading this thread from the start and have been in ur shoes many times matey......

 

Have you changed the ECU? Do u have a series II PTU? Does ur 300 idle well? Do u get black spots on the rear bumper?

 

Alz.

 

popped my chipped ecu, so running standard one which is doing the same, have series one but tried a couple making no differance, idles great well better then ever, stays exactly round 750rpm on clock but if you really sit in drivers seat with hand on gear stick you can feel it moving around a little but you really have to feel for it,

 

My car is white and a few hours of driving after washing it i get a black rear bumper lol but again its allways done this,and that was with chipped ecu have not drove it much with standard ecu and have not washed it so its black anyhow lol.

 

Cheers for reply mate, dont worry next time i spin the car about i will be in love again.

 

Thing is im a mechanic and cant find out whats wrong, would rather a blown turbo or something atleast i know where i stand,

 

might have to take boonet off and and get in engine bay and let me brother drive it up the road so can have a fiddle when its doing it, (only joking)

Cause when its on the drive it revs perfect unless i blip the throttle to 2100 rpm and get a big bang. but all happens to quick to find anything.

take the PTU off and give the prongs another clean, when i accidental fitted a clapped out PTU instead of my working one, it idled fine but soon as you came to drive it, it sputtered and jumped and backfired like a bish.

 

when you checked the timing did you do so with a timing light? as mine had a strange misfire on idle when it was out.

 

Had ptu off again today and cleaned it still same, also timing when set at 15btdc it backfires worse but if i turn ptu to its maximum dont backfire as loud but still their thats why i took cambelt off all marks are dead on now and still the same and timing back at 15btdc.

 

Thank you.

could stick it on a rolling road then you could more or less do that lol it helped me track down an annoying squeak that i thought was comming from the suspension turned out it was a belt shame i found out after i had the front shocks done

I have the same problem to sort out. I've plugged mine into my conzult and it seems i have a problem with No4 cylinder which i have to sort out yet. My backfire only comes from the passenger side exhaust and only dose it when the engine warms up. I'll let you know when i find the cause Terry might help you out.

i had the same problem or all most only happend when it was warm/hot .. it was my O2 sensor i unpluged it and it solved the problem

id have thoght it would be missing all the time if there was a break not just under load, i guess it could be the coil pack itself have you tested how far the spark jumps from the spark plug thatll give you an idea of coil strength and have you checked the gapping on the plugs is right?

 

They all look very similar how far they jump around an inch, at a guess,

Have not measured gaps their new plugs but bosch ones so was waiting for a set to be sent of ngk to make sure it aint them.

 

Thought it may have a break in the wire that under certain conditions breaks the contact and the touches again making coil spark. but have wiggled everything with no joy.

could stick it on a rolling road then you could more or less do that lol it helped me track down an annoying squeak that i thought was comming from the suspension turned out it was a belt shame i found out after i had the front shocks done

 

If i cant find it i will wait to after christmas and call geoff only problem is would have to stay their till its done sure he would solve it in no time.

 

Well atleast you got new shocks lol

I have the same problem to sort out. I've plugged mine into my conzult and it seems i have a problem with No4 cylinder which i have to sort out yet. My backfire only comes from the passenger side exhaust and only dose it when the engine warms up. I'll let you know when i find the cause Terry might help you out.

 

Many thanks and if i solve mine i let you know,

Goodluck to us both.

i had the same problem or all most only happend when it was warm/hot .. it was my O2 sensor i unpluged it and it solved the problem

 

hi mate I will un plug them tomorrow and let everyone know thank you for reply.

Had ptu off again today and cleaned it still same, also timing when set at 15btdc it backfires worse but if i turn ptu to its maximum dont backfire as loud but still their thats why i took cambelt off all marks are dead on now and still the same and timing back at 15btdc.

 

Thank you.

 

strange, when i replaced my mapped and socketed ECU, the cas was all the way over to the left timing was at 15btdc and i had a misfire on idle.

 

Put my socketed ECU back, timing was 30 degrees out on the crank pulley, so redid the timing and its now running smooth as, just over heats lol, sounds like you may have a dodgy ecu if your timing is at 15dbtc and the cas is all the way over. im sure when the cas sits like that, the engine cant advance the timing how it should when it needs to.

strange, when i replaced my mapped and socketed ECU, the cas was all the way over to the left timing was at 15btdc and i had a misfire on idle.

 

Put my socketed ECU back, timing was 30 degrees out on the crank pulley, so redid the timing and its now running smooth as, just over heats lol, sounds like you may have a dodgy ecu if your timing is at 15dbtc and the cas is all the way over. im sure when the cas sits like that, the engine cant advance the timing how it should when it needs to.

 

Hi sorry may have miss wrote that its 15btdc roughly in the centre, but didnt have the light until today and turned the cas yesterday fully anti clockwise to advance the timing and it gets better so thought it could be cambelt issue so pulled cambelt put it back on using marks on belt, then set timing 15btdc but get popping and backfire but if i advance the cas to its max i get popping but no loud backfire, but its set back at 15btdc and its done it with both ecu,s.

 

The only other thing i was thinking about what i have not messed with yet is the varible valve timing solenoids anyone ever had a problem with them.

Terry this engine you presently have, did you install it as is or did you use bits from the other engines in particular any of the cam sprockets? and what year engine was it?

 

Jeff

Terry this engine you presently have, did you install it as is or did you use bits from the other engines in particular any of the cam sprockets? and what year engine was it?

 

Jeff

 

Hi jeff fitted it my self, left everything on it turbos loom the lot acctually unplugged the loom from the ecu end on both engines and plugged it back in at ecu end.

 

Even used ecu from donor car, when fitted it was running fine,

 

Mines a 1989 and pretty sure donor was a g reg too.

Just a thought but you said you went from auto to manual, have you done the bypass for the neutral switch (i think that was it) as that will mess up the CAS timing

just to add to have you got a TT fuel pump and ecu or NA ones maybe a mix, and what about the gearbox ecu auto or manual

just to add to have you got a TT fuel pump and ecu or NA ones maybe a mix, and what about the gearbox ecu auto or manual

 

Hi mate,

 

converted it to manual then re shelled it using manual car, so have all manual loom,

 

neutral switch seems to be ok cause when put foot on clutch and put it in gear revs raise a little,

 

Ecu is twin turbo and fuel pump was working fine just started playing up.

 

Thank you.

Been doing a bit of research on my backfire problem and have found a few comments about the EFI loom (the part that runs at the back of the engine) getting crushed when installing the engine. Might be worth checking Terry

Been doing a bit of research on my backfire problem and have found a few comments about the EFI loom (the part that runs at the back of the engine) getting crushed when installing the engine. Might be worth checking Terry

 

Cheers looked today all seems good with the loom.

 

Been looking at everything the last couple of days and cant find anything wrong,

Changed a coil and have lost the hesitation under load its driving great now.

 

But still have the backfire in neutral when i rev to 2100rpm. Have actually noticed it does this when driving too.

 

But does not do the backfire at all until its warmed up.

 

I think the air regulator on these cars must work like some sort of choke was wondering if this could do it,

And only other thing i aint checked is the fuel pressure cause dont have the tool at moment.

 

Maybe its just me being fussy cause it drives fine, but it never use to do it and and on the run down in gear from 2100rpm you can feel the car jerk back and forwards very slight as its popping.

 

Unplugged o2 sensors made no differance,

 

Oh well suppose i should be happy it aint smoking and its running.

 

Cheers 4 all your replys guys.

If unplugging the o2 sensor made no difference... then its a dead o2...

But i would also suspect your AFM and PTU.

But i would also suspect your AFM and PTU.

 

Hi mate changed afm and ptu no differance,

 

as far as im aware will run rich with no o2 sensors, But if you have a faulty one can cause problems with ecu and cause it to mess around,

 

So unplugging them for a run up the road would show this, but have the same problem plugged or unplugged.

 

Cheers for your reply.