Turbo Nova miss-firing?

[bodleytunes]

Hi peeps,

I recently got my gear linkage fixed and a few days later after the day I picked up the car from the garage, I noticed it wasn't running right when the turbo spools up.

Off boost its totally fine, loads of low down power, no missing at all, but when I floor it and the revs and boost build, it suddenly changes it's tone, and sounds a bit like a scoobie (burbling / 3cylinders?) and looses a bit of power. Also sounds like it maybe popping a bit from the exhaust when it does this. Also note it doesnt lurch and loose all power, just a bit really. But somethings def not right.

At first I thought it may be the spark plugs that need changing, it does use a bit of oil, think the valve stem seals are a bit nakered as it smokes now and again at idle so I thought they may be fouled up.

Changed the plugs and its still the same.

I've hardly drove the car really and it was fine before I took it to the garage. I@m just hoping they didnt take it for a spin and rag the f00k out of it and over heat it or something as it has a manual cooling fan switch.

Any ideas what it could be, Ill try to get a video of it but its all snowed up round here at the moment.

Sometimes if you gently feather the throttle so that turbo spools slowly then it doesnt happpen, but if you floor it normally it does when it builds full boost and higher revs.

Its seems to be boosting normal pressure, which I think is around 0.8 / 1.0 bar.

Cheers,

Jon.

[bodleytunes]

I think it could do with a run on a rolling road and someone who knows there stuff to put it through its paces.

Anyone know a good one near stockport area?

[Adam]

What is it? A LET???

Is it a standard engine??

[Jack]

What condition were the plugs when you took them out?

[bodleytunes]

What is it? A LET???

Is it a standard engine??

yeah its a C20LET engine, running 250bhp (phase 1).

The plugs looked fine! Nothing wrong with them didnt look like running lean and didnt look all mucky either!

Cheers,

Jonathan.

[craig green]

But have you correctly gapped the plugs?
Also what plugs (brand, heat range) Have you used?

Try & Earth the alternator bracket, with a suitably fat cable, to the negative battery terminal to rule out a poor earth.

[bodleytunes]

I've not gapped them no.

its doing exactly the same thing with the new plugs as the old plugs.

They are NGK BCP7EVX I think that I bought as they were recommended on Migweb for phase 2, which is what I was going to go for once I upgrade the fuel pump etc.

Cheers,

Jonathan.

[Stoo]

Leads or coil

FACT

[Rickardo]

Sorry to hear about the Car Jon, it's my old motor.

I changed the plugs, leads and coil earlier in the year. All new items.

Gear linkage was new as well, what happened to it?

Only problem is what, if anything have the garage done to it. They wouldn't own up to going out in it even if they did.

[craig green]

In that case, gap them. All plugs need gapping when new. I think the recommended gap is about 0.6mm.

Maybe google plug gaps next time you are bored.




Only problem is what, if anything have the garage done to it. They wouldn't own up to going out in it even if they did.

That had crossed my mind...... [edit] Funk giving a LET'd Nova to a garage (& letting it out my sight)

[bodleytunes]

I've left them at standard gap.

Thing is why was it fine with the old plugs, hardly ever miss fired with them - did very rarely and then it was just a single miss and pop rather than constant.

Could it be the extra cold air, more dense and blowing the spark out??

I've never driven it in such cold weather you see, and its only started doing this since we have had this cold streak of weather.

[bodleytunes]

It's not the new plugs causing the missfire, it was doing it with the old plugs!

I changed them to see if it would fix it and its the same?

[craig green]

No, it should go muchj better in the cold. Gap the plugs properly to 0.6mm.

[bodleytunes]

Not sure about the gear linkage, it happend when my old dad drove it haha.

I hope they haven't ragged it at the garage, I'm hoping maybe its the cold weather.

Also the Alarm went mental after a flat battery and has reset itself to default or something, now its flashing on the dash all the time and you cant turn it off, no sound though although I did set it off that time by accident and nearly went deaf!

I've got a buyer for my RX7 now too so would like to be able to drive the Nova.

I haven't changed any boost settings either, I'm not daft enough to do that! :)





Sorry to hear about the Car Jon, it's my old motor.

I changed the plugs, leads and coil earlier in the year. All new items.

Gear linkage was new as well, what happened to it?

Only problem is what, if anything have the garage done to it. They wouldn't own up to going out in it even if they did.

[Rickardo]

That had crossed my mind...... [edit] Funk giving a LET'd Nova to a garage (& letting it out my sight)

Agreed.

Thats why i did all my own work.. How many garages have actually seen a Let Nova.

[craig green]

Thats why i did all my own work.. How many garages have actually seen a Let Nova.

Not so much a case of seeing it, but being let loose on a 'test drive, just to the cake shop' type of scenario, in this weather!! Jeez.

[Rickardo]

Not sure about the gear linkage, it happend when my old dad drove it haha.

I hope they haven't ragged it at the garage, I'm hoping maybe its the cold weather.

Also the Alarm went mental after a flat battery and has reset itself to default or something, now its flashing on the dash all the time and you cant turn it off, no sound though although I did set it off that time by accident and nearly went deaf!

I've got a buyer for my RX7 now too so would like to be able to drive the Nova.

I haven't changed any boost settings either, I'm not daft enough to do that! :)

The day before you bought it it was on the Rollers. Boost was 0.8-1.0 bar. It has the manual boost controller on it, so it won't overboost.

In the cold it should feel quicker, why don't you turn the boost down a touch and see if that makes it any different.

[bodleytunes]

I was hoping this garage might treat it with respect, as the guy is into rallying and has a escort mk2 with cosworth engine and other similar cars in his car park.

Yeah I could try reducing boost, although the boost seems to be exactly the same as before 0.8 / 1 bar.

If you gradually press the throttle so the engine has time for the turbo to spool and gradually build boost and revs it sometimes doesnt missfire, strange.

Doesnt seem to be pinking or anything and didnt notice any smoke from the back.

I did read on one thread that a dodgy turbo can cause missfires if the seals are gone and it pumps oil into the cylinders but I've not noticed clouds of smoke or anything on boost.

It just smokes a bit on idle, but my astra did that, valve stem seals probably.

I'll try gapping the plugs also, and if that still no worky, might try taking it to a rolling road.

Would it be an idea to Reset the ECU somehow? Earthing it or something?

[Adam]

Check for boost leaks.
Also does the ecu light come on when it starts missing????

[Lee H]

Smoke on idle will 99% be turbo seals and not valve stem seals.

As for the problem, sounds like a dodgy coil or amplifier to me.

Might be worth throwing a new coolant temp sensor in as well for what they cost.

[bodleytunes]

It only smokes now and again, usually when at traffic lights after the engine has been running a while. Smoke is white and a bit smelly.

I'll re-gap the plugs and take it for another spin, and video it this time, when the weather improves, I'm not bothering taking it out when its like this.

Cheers,

Jon.



Smoke on idle will 99% be turbo seals and not valve stem seals.

As for the problem, sounds like a dodgy coil or amplifier to me.

Might be worth throwing a new coolant temp sensor in as well for what they cost.

[Lee H]

It only smokes now and again, usually when at traffic lights after the engine has been running a while. Smoke is white and a bit smelly.



100% turbo seals now you've added that bit.

[vaux nut]

this could be a shot in the dark pal but i had the same problem with my astra gte turbo it ran on three an barbeled and it was the fuel pump causing it losing fuel pressure it just couldnt cope replaced this and it fetteled it:thumb:

[Paul]

If the cap is not a genuine Vauxhall one, it can cause misfiring under boost. Even if it is a brand new one.

[bodleytunes]

why was it not missfiring under boost the last few months!

If it was the cap surely it would be doing it all the time?

Its only done it the last week?

The only different factors to take into account at the moment are that it just came out of the garage to fix the linkage and also the weather is very very cold.

Cheers,

Jon.

[bodleytunes]

Was you astra only running on three when on full boost? Coz mine is.

Off boost it runs smooth as silk and just as much grunt as ever.




this could be a shot in the dark pal but i had the same problem with my astra gte turbo it ran on three an barbeled and it was the fuel pump causing it losing fuel pressure it just couldnt cope replaced this and it fetteled it:thumb:

[Sloth]

sounds like its running lean under boost, check your vac pipes around the manifold, if the garage have knocked the one to the reg and split it, it wont fuel right. id be back at the garage asking what exactly they touched.

[bodleytunes]

I thought it would be making a pinking / knocking sound if running lean?

As far as I can tell it just sounds like the burble sound of 3 cylinders and a drop in power.

[Sloth]

it depends, if its cutting fueling under boost, possibly not. the other option is a dodgy injector, when were they last cleaned?