Fuel cut(?) / cutting out on boost

Posting on behalf of TRD-Rob

The car suddendly developed fuel cut like symptoms this morning. Car drives absolutely fine off boost and under partial boost. Boost controller is turned off (0.7 bar ish normally).

When it hits 0.7 bar for a fuel seconds it the engine suddenly cuts for less than a second, then comes back in again. It's feels exactly like fuel cut. There's also a bit of a pop from the exhuast.

Any ideas why it would suddenly develop these symptoms? He didn't have the datalogit box with him so we can't datalog anything at the moment.

We checked the usual stuff - IC pipes all seem secure, no obvious boost leaks, everything is connected up okay, AFR's are spot on, drives absolutely fine except this apparent fuel cut when at full boost.

Spec:

PowerFC ECU

650cc injectors

6spd BPU

Hybrid turbos

Full decat & NUR Spec exhaust

Nothing stupid like the FCD playing up?

Plugs are near new and it's a complete cut of power, so can't see it being them in this curcumstance.

Nothing stupid like the FCD playing up?

It's got a powerFC Jay, so no FCD

When I had a missfire it seomtimes was so violent it felt like fuel cut, have you checked the coil pack clips? Would also explain the pop with unburnt fuel going through

When I had a missfire it seomtimes was so violent it felt like fuel cut, have you checked the coil pack clips? Would also explain the pop with unburnt fuel going through

When I had a missfire it seomtimes was so violent it felt like fuel cut, have you checked the coil pack clips? Would also explain the pop with unburnt fuel going through

Coil pack clips are all new I believe (for certain a few were replaced, but not sure if all were). Will check with Rob tomorrow, thanks guys.

It honestly feels like all 6 cylinders are cutting, never felt a misfire this violent before! However, as you say, the pop from the exhaust does seem to indicate some unburnt fuel is getting into the exhaust... It also made some big flames on a 6k rpm gear change when I was driving, which Rob said it doesn't normally do. Not sure if thats relevant!

It's not so much the clips themselves I've found, it's the pins inside them. Have you followed Ian guide by pushing a small screwdriver in the back of the pin to close the gap? Changing the plastic clips did nothing in my case, it was the pins inside that I had to keep an eye on.

It's not so much the clips themselves I've found, it's the pins inside them. Have you followed Ian guide by pushing a small screwdriver in the back of the pin to close the gap? Changing the plastic clips did nothing in my case, it was the pins inside that I had to keep an eye on.

I should have mentioned this in the last post, Ryan closed up all the clips when we did the mapping late last year. Good point though

I should have mentioned this in the last post, Ryan closed up all the clips when we did the mapping late last year. Good point though

I needed to do mine on a regular basis, about once every 6 months. When I took the clips apart the pins had moved right back so they were making next to no contact with the coilpack side

My moneys on the plugs Darryl. I've just fixed a supra with exactly the same symptoms but it continued to splutter. On closer inspection the plugs were that bad they has broken the tip off. New plugs later and it's pulling like a train.

Fitted a new set of plugs today but it's still doing the same.

All coil pack connectors are new (replaced about 1500 miles ago), also tightened the connectors as suggested.

Rob is taking the car to Ryan on Monday to see if the ECU can give any hints as to whats going on...

Bit of a long shot here, but could this be an indication of one of the turbo's failing? I really hope not..!

Highly unlikely I'd say, seems more electrical if anything

Highly unlikely I'd say, seems more electrical if anything

I am hoping/expecting that too, my fairly limited engine knowledge is saying it's ignition related, which narrows down possible causes massively.

Little update - Ryan checked this today but could not solve it at the time. Awaiting more info from Rob, but apparently it looks like a sensor issue. Ryan mentioned that there were two possible sensors at fault. I'm guessing one is the CPS but not sure of the other one...

sounds exactly the same issue i have with mine at the minuite ryan took alook last week and has told me to change the camshaft sensor or the crankshaft sensor,

can you please post up the results of how you solved your problem[COOL][/COOL]

Mine is starting to do this too, i fitted a decat pipe last week, so i am just running the first cat, it has been running fine untill today,started her up pulled away (swiftly ) then i got sudden power loss for about 1 second , so if you managed to sort yours out ,could you please pass on the information, thanks....mark

Mine is starting to do this too, i fitted a decat pipe last week, so i am just running the first cat, it has been running fine untill today,started her up pulled away (swiftly ) then i got sudden power loss for about 1 second , so if you managed to sort yours out ,could you please pass on the information, thanks....mark

Have a read here: bpu Your one will be fuel cut or spark plugs if you've not done the BPU mods.

Robs and Mikeys issues are something else since they are running standalone ECU's.

Have a read here: bpu Your one will be fuel cut or spark plugs if you've not done the BPU mods.

 

Robs and Mikeys issues are something else since they are running standalone ECU's.

Thanks for that, the problem is that i was only at 0.6 bar at the time, and didnt notice any warning lights, if it was the spark plugs wouldnt i just feel a missfire and not a sudden loss of all power for about a second!!! unless they all packed in at once , which would be highly unlikely.

Can't say for sure but I think Michel and myself had something similar to this and it was a dodgy earth or contact on the ECU, albeit AEM. Was a while ago though so can't 100% remember

Thanks for that, the problem is that i was only at 0.6 bar at the time, and didnt notice any warning lights, if it was the spark plugs wouldnt i just feel a missfire and not a sudden loss of all power for about a second!!! unless they all packed in at once , which would be highly unlikely.

Could you please start a new thread in technical to discuss your issue Mark? Robs and Mikeys ones are a bit different in terms of the troubleshooting route as they have standalone ECU's and have had the common items rules out already.

mine is going in to see paul at whifbitz friday hopfully he can get to the bottom of it ive given up now:search:

ill post my results up as soon as i know homer;)

Thanks mate. Rob's off on hols at the moment so haven't had chance to fit the CPS yet...

Little update on Rob's car:

Crank position sensor was swapped - no difference

The misfiring has got a lot worse over the past couple of weeks, it's doing it off boost and is even misfiring slightly on idle.

So, cam sensors are next but I am doubtful if they are really the cause. Have also advised him to check the ECU earth as mentioned earlier.

Very frustrating for Rob after spending so much money on the car and now not able to drive it at all..

mine is all sorted homer:)

it turned out mine had somthing turned on the map/ecu from when it was an auto, it was retarding the ignition thinking it was about to change gear

robs car seems to have a bigger problem sorry i couldn't be of any help i hope you get to the bottom of it:)

No problem, thanks for the update Mikey, glad you got to the route cause

One further thing Rob found today - he has disconnected the boost controller, the car is now running at 0.7 bar and seems to be running better (the odd misfire, but mostly okay). However it still didn't idle perfectly so there's still an apparent ignition issue somewhere. Lee P will hopefully have a quick look at Ace Cafe.