cr80442
I have been having a cutting out issue on my 740 turbo. It only happens at throttle positions more than say half but it mainly happens at WOT. Bassicly it's like the engine completly cuts out for a split second then gets going then does it again and so on. I have replaced my Ignition leads which needed to be done anyway but that didn't improve it. I have cleaned and checked the main engine lome connecters and they seem fine. I've checked the ballast connecter as well. Also noting that when it cuts it sometimes missfires as well. Bassicly the things I can think of that would cause this would be the sensor in the dizzy or faulty EZK and ECU. Any ideas? Any help would be appreciated cheers.
DELETE OLD THREAD IF NEEDED.
Vee_Que
If the cap and rotor are fine, then Fuelling. Have you got a new fuel filter on it? How are the injectors? What boost is it at?
cr80442
Vee_Que;117132 wroteIf the cap and rotor are fine, then Fuelling. Have you got a new fuel filter on it? How are the injectors? What boost is it at?
Not sure about the fuel filter will definitely change it anyway. No idea about the injecters I've checked connections tho they are fine. Running stock boost
Dauntless
Which spark plugs are you running? I had good luck with NGK BPR7ES at 0.7mm gap. Having said that, it doesn't sound like an ignition issue to me either.
I'd definitely change the fuel filter. Do 740 intank pumps ever get weak like 240s do?
cr80442
it has NGK plugs BPR7ES I haven't changed the gap.
jamesinc
They'll have a default gap of 0.8mm, but I used to run them all the time like that up to 13psi and never had issues.
I'm also joining the "it's a fuelling issue" club, as fuel flow corresponds most closely to load. Start with the filter, then if the problem persists move on to the FPR, then pumps, then injectors themselves. The injectors have little filters in their inlets that could clog, though I wouldn't expect that to happen unless you had a serious failure of the main filter.
Dauntless
It's always worth setting the gap when installing spark plugs, they can vary out of the box.
Is there any fuel in the vacuum hose to the FPR? Is that hose split?
cr80442
Dauntless;117150 wroteIt's always worth setting the gap when installing spark plugs, they can vary out of the box.
Is there any fuel in the vacuum hose to the FPR? Is that hose split?
I checked the FPR vaccume line it's fine.
cr80442
So today I cleaned and checked both the ecu and ezk connectors. I cleaned both although it didn't make a difference. I also tried unplugging the TPS and taking it for a test drive and it didn't make a difference as well. The only things now that could cause it that I haven't checked are the hall effect sensor. (I checked wiring it's fine) and the knock sensor and the ignition coil.
cr80442
jamesinc;117147 wroteThey'll have a default gap of 0.8mm, but I used to run them all the time like that up to 13psi and never had issues.
I'm also joining the "it's a fuelling issue" club, as fuel flow corresponds most closely to load. Start with the filter, then if the problem persists move on to the FPR, then pumps, then injectors themselves. The injectors have little filters in their inlets that could clog, though I wouldn't expect that to happen unless you had a serious failure of the main filter.
When the car cuts out it sometimes miss fires as well. Could fueling really cause that?
jamesinc
Yeah, not enough fuel (clogged filter or other issue) = lean running = misfires
cr80442
jamesinc;117162 wroteYeah, not enough fuel (clogged filter or other issue) = lean running = misfires
Tomorrow I'll replace the filter, it's a service item anyway and they look to be cheap.
cr80442
It does sometimes cut out at low rpm but rarely
Vee_Que
They aren't cheap, even a ryco one is $40 trade price.
cr80442
Vee_Que;117168 wroteThey aren't cheap, even a ryco one is $40 trade price.
Hot dayum
cr80442
The car was sitting since 2005 so I think a fuel filter change should be done either way definitely a stage 0 item
cr80442
Today's update for the 740, disconnect the overboost switch, made no difference, changed out the coil and for some reason it idles low now but it didn't make a difference to the cutting. Tomorrow I'm replacing the fuel filter. Pray to the Volvo gods that fixes it
cr80442
Today's update, replaced the fuel filter and ITS FUCKING FIXED, excuse my language but I'm so happy it's finally fixed
Vee_Que
I only suggested it a week ago!
cr80442
After a second drive the problem has come back. Ughhhhh