Engine not playing the game - intermittent cutout below 3000rpm

Hi.
 
Moved to Mt Isa last year and my MR2 was trucked up. Has sat in the shed since it got here waiting for things to settle down to get the turbo sorted. Planning a road trip next month that will see me head for the east coast from Mt Isa then follow the coast from Townsville down to the bottom of Australia and along the south coast into Melbourne. then home back up the guts. 7,000kms roughly and some of these K's will be in some pretty isolated areas!. 

So, got a GCG steel wheel turbo (just ct26) and took it to a local mechanic. he fitted the turbo up, everything looked good. sat it on the dyno and started giving it some runs and the engine would kind of cut power just a smidge under 3,000RPM and start bogging down.

So, found a small hose off and put it back on. it ran to pull some dyno runs. big disappointment in the dyno figures. it was ranging from 108 - 116Rwkw with boost hovering between 8lb and 10lb. 

I put a boost Tee in and gave it 2 clicks to pick the boost up slightly (as it was clearly over fueling something shocking) and it still only pulled the same figures the only difference being that it picked up faster than on stock boost. (Boost was eventually increased to 12.59lb before I backed it down a bit)

Decided to just drive it home and think about it. pulled out and drove down the road and bang the engine started doing the same thing cutting just before 3K. 

too it back gave it a look over. couldn't find anything. I told them not to worry about it i'll bring it back later in the week and throw it back on the dyno to check it out.

Then on the way home it drove nice. 

Does anyone have experience with this cutout?. a few things to note:

- Exhaust is currently a straight through single system - straight off the turbo to tip (for the track only use of course)
- Engine is 3,000kms old - Forged Pistons, H Beam rods, new crank, fully balanced, ARP head studs and bottom end studs etc. 
- Stock ECU for now and was meant to be running stock boost for run in period.
- The new turbo fitted is a slightly modified GCG rebuilt CT26.


I have the following thoughts to check this week:
- With battery terminals being taken off and on over the past few days - perhaps the MAF or something is stuffed?
- Timing - Not sure if the timing should be advanced etc?. unsure.
- Was thinking fuel pump or filter initially but then it plumes smoke out the arse and reaks of fuel. its over fueling.

I appreciate if anyone has any thoughts. I have more items to add to this build and was hoping to get at least some of it done before I do my 7,000km road trip in June. but I am not going to do anything further until I can get it running smoothly with the stock ECU etc and I know everything is spot on.

Cheers.

So many things it could be, try getting out the ecu fault codes, check compression and leak down, try replacing fuel filter first and dump your fuel from the drain hole and add new fuel, air filter, check for vacuum leak, clean the throttle body and check sensors (tps, maf)...
Dyno should be giving you read outs of air/fuel ratio to know what's happening....

okay. Found a 7.5 AMP ECU fuse in the front fuse box that was blown. replaced it, made no difference. 

removed the vac line off the inlet manifold and blocked it off - boost lasted a lot longer but it cut out again with the CEL back on.

So, back to the drawing board.

- Ordered a Turbosmart FCD (electronic version) this afternoon. hopefully it will be here next week. 
- Will order a new Knock sensor (Toyota want $311.37 so will look elsewhere)
- Potentially remove fuel pump and sock, might change it just in case
- Then check wiring and search for any exposed wires or bad terminations. 

Might end up going to a PNP ECU if all else fails. was planning to down the track anyways but just not yet since im only running it so mildy.
 
This is becoming frustrating. so far away from anyone with in depth knowledge of these cars so it will be hit and miss for me.

Yep had cap failure with ign related symptoms, so good suggestion.

 
okay. the saga continues I guess.
 
Threw my old leads on (were running fine when i pulled them off the engine.) it still cuts out. 

Found the Knock Sensor was loose and wobbling in the thread so have tightened it up. The knock sensor appears to be the ATS adaptor and chevy KS. so i may replace this with the stock unit just to rule it out. 

Spark plugs all look great. its idling fine. today it let me get under boost and rev up through to 5K before it cut out again and flashed the CEL. 

I've put it back in the shed on ramps. will get back under it and keep looking blankly at it swearing intermittently at it. (I find this helps...)

- Oh and does anyone know what size the nuts are on the AFM?... 
 
cheers.

Afm screw was approx 24mm in from edge of hole. The number on the side states 71. I took that as 17.1mm from reading on here. So ive backed it out to approx 17.1mm
 
Ill take it for another run now. Hopefully it doesnt go BANG!!.
 
when i get back if its still no dofferent ill remove ecu and have a look at the capacitors. Thanks heaps for those pics, i would have been like a 5 year old looking into a lego technics box with that kind of stuff.
 
Does the backing off of the afm lean it out or richen it up?... chances it could blow up?.... 

Treay81
 just under 10lbs but it cut out at just under 60kph

 
Fixed that for you
 
That said, good to see your making gains.  Sounds like a combination of a lot of maintenance items.

 
Installed thermo fan in engine lid, still have the vacuum lines from inlet to boost pressure sensor blocked off. 
 
Put the car back on the dyno this afternoon. fuelling was okay, between 10.53 up to 12.5 so, safe enough for my trip to  Melbourne Next month.



 
My horsepower and torque has improved but only slightly. so it is now putting down 153RWKW and 350nm. So its about stock at present i guess. 
 
Once i get back from my trip i'll look at new intercooler, fuel system, ignition and perhaps a Link G4 ECU. 

at least for now its running nice enough to do the trip.