Misfire, stuttering, pops and bangs?

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BALDYMONSTER
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Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

The car has had this almost imperceptible issue for a few weeks now.

The sort of thing you only really notice if it’s your car, if that makes sense? It just wasn’t accelerating as hard and I could feel a bit of hesitation nagging away with the foot down in boost.

Well last week I floored it in third joining the motorway and thought I’d hit over boost. But for the moment the car just farts, misses, bangs after about 3000rpm under load on boost.

It seems to be slightly less prone to do so when the tank is full of fuel and it’s really bad on a quarter tank and under. It had a new walbro 255 fitted after Peter Gidden lied through his teeth, as usual, and fitted a cheap eBay pump for £19 instead of what I’d paid for about 2 and a half years ago.

It’s had new plugs, dizzy cap seems fine and has been cleaned up.

It’s always run on V-Power.

Has anyone else had a similar issue?

I’m leaning towards a knackered pump or dirty fuel filter, but would appreciate others thoughts.

Thanks.


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Re: Misfire, stuttering, pops and bangs?

Post by rgb »

damp in the coil makes them run like that
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Re: Misfire, stuttering, pops and bangs?

Post by simpson_eh »

As above
Check for cracks in the coil had the same symptoms
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

I’ll take it out and have a look next week.

Still no fault codes showing.

Hope that’s the problem and not the fuel pump.

Thanks for the help.
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Re: Misfire, stuttering, pops and bangs?

Post by MR2madlad »

Do a fuel pressure test on it to identify if pump is weak, might be once the fuel level is lower than pump body its drawing in air by badly made / sealed pump.

Check / replace fuel filter.

Check for leaks on fuel lines.

if you have replaced all the service bits dizzy, arm, plugs and timing is ok the next step for me would be to check coolant temp sensor the green one that reports engine temp to ECU (not gauge) to BGB specs if that is good the Lambda probe would be my next port.

My 94 Turbo had bad Lambda probe and was kangarooing like crazy when warm, from cold ran ok but once hot no guts under 2500 RPM had to keep pressing accelerator then finally it takes off like crazy.

Tested Lambda with gas torch on volt reading on meter end was virtually glowing bright orange 0.0034 volts (best part of FA!) the heater was also open circuit.

Got new one (genuine Denso off ebay which was a genuine Toyota one that had the P/N slightly ground off so Denso sold as a DOX-0216 4 wire, properly left over factory that Toyota didn't buy looked identical even the welds so 100% genuine) warmed that up with gas torch the voltage it stuck out went to 0.8 - 0.9 v quick and instantly dropped to 0 when torch was taken away so old Lambda was fxxxxd.

Fitted the new on, she runs soo much better.
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

Fuel pressure checked today.

Was showing a consistent 50 odd psi, is that about right?
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Re: Misfire, stuttering, pops and bangs?

Post by benckj »

Should be 32psi at idle after the regulator. Does it go up when you increase RPM?

From your description I doubt if it’s fuel related.I’d check the electrical parts listed above and pop lid off ECU to see if any of the capacitors have leaked acid onto board or have an odd shape. Grounds are also very important in engine bay. Remove & clean rather than just visually inspect.

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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

The psi doesn’t change at all, idle or increasing the revs it stays the same.

I’ll check the ecu board tomorrow.

Could it be the map sensor?
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Re: Misfire, stuttering, pops and bangs?

Post by benckj »

Fuel pressure should increase with RPM. Check the vacuum line off the regulator to see if split.

Doubt if MAP sensor as would cause all sorts of serious issues including start-up. Could have water in any number of connectors or bad ground wires. Just need to methodically go through each section of engine bay looking for cause. Don’t just inspect without pulling apart each connection or hose and then clean & reinstall.
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

Well I cleaned every single plug in the engine bay and refitted them then cleaned the ecu plugs and checked the board. Everything was dry and looked perfect.

Still stuttering and dying under boost.

:(

I’ll try a smoke test on it this week and se if that shows anything.
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

Smoke test done, cant see any leaks.

Swap for decent motorbike, streetfighter or sportsbike.
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

New leads fitted, still the same.

New coil pack next week.
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Re: Misfire, stuttering, pops and bangs?

Post by BALDYMONSTER »

So something else has started happening now.

When at idle the car stutters on occasion, it doesn’t stall and there isn’t any pattern to how or when it does this.

The rpm just drops momentarily.

Can anyone draw a link between the two issues? Anyone had similar?
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Re: Misfire, stuttering, pops and bangs?

Post by Voivod »

BALDYMONSTER wrote: 19/02/21 18:39 So something else has started happening now.

When at idle the car stutters on occasion, it doesn’t stall and there isn’t any pattern to how or when it does this.

The rpm just drops momentarily.

Can anyone draw a link between the two issues? Anyone had similar?
Is it Rev1 2 or3 ?
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