NINJA DAVE

Hey folks, i'm running a 94 wrx import, it's got a few mods,hks fuel cut defender, uprated pump, blitz boost controler, apex induction kit, full ab vortex system, some other stuff, just had a new short block and engine rebuild, it uses a U8 ECU, the car is adjusting the timing by 14 degree's i was advised (basically limp mode) there are no warning lights or fault codes, the sensors have been checked and other related things that could cause this correct compression etc., i'm now left with the ECU and wiring loom, i have a great mechanic working on this car who has an excellent reputation but he is also at a loss with this, anyone got any suggestions? I'm getting another U8 ECU on wed to try this weekend but my recent luck will no doubt continue and the ECU will be fine, i've spent a good bit of cash on this over the last 3 mnths and i'm really loosing faith in the whole thing to the point i want to take a big hammer to it, any help or advice would be much appreciated.

Thanks Dave.

NINJA DAVE

Forgot to say i was gonna put in a power fc and controller but was advised that working round a problem is not the solution and that it wouldn't make a difference if it was not ECU related.

Thanks again. Dave.

Scott.T

iTrader: (2)

Limp home AFAIK comes in 2 forms :

1.Limits boost to 0.5 bar
OR
2. Will cause fuel cut if you go above 0bar or approx 4000rpm

Not sure how it was decided it's pulling 14 degree's. The ECU will run the maximum timing allowed/indicated by the knock sensor.

jaytc2003

iTrader: (1)

try removing the fuel cut defender and maybe the boost controller. See what happens then. If it gets better then add one component at a time.
If its a new engine as well check that all hoses and sensors are connected up to where they should be.
Cam timing, and also were the heads disassembled when it was rebuilt?

ZEN Performance

The car will run in limp mode if the timing is progressively back to the point that it is running very little of the additional correction map. It will do this if it hears what it thinks is detonation.

The most important thing, is has the car been run with a reset ECU and a set of det cans to see if the car actually dets or not?

The ecu putting in a 4000rpm rev limit is usually linked to speedo issues.

The fact that it has had a new short block is significant. I would check the cam timing, check that it's not misfiring on load (which can cause detonation), also check for fuel supply issues. A failing pump can cause leanness that will lead to det, as will a split inlet pipe, or a missing breather hose etc.

NINJA DAVE

[QUOTE=Scott.T]
2. Will cause fuel cut if you go above 0bar or approx 4000rpm

QUOTE]

That's what it's doing, above 4 grand it's all over the place. Attached the knock sensor to the bulk head to eliminate that and it was still retarding the timing?

Engine has done 1400 miles since rebuild, didn't find the fault as it's not been above 3000rpm until now(1200 miles).

It never done it with the boost kit in the past only once the engine died and i got the rebuild has it surfaced? Could anything to do with the rebuild have upset the ECU or damaged it?

The heads were removed but were rebuild with all required work and there producing perfect compression.

ECU is a U8, do i have other options with ECU's as i'm having probs locating a U8?

Really appreciate the help with this as it's starting to get me down.

jaytc2003

iTrader: (1)

were the coilpacks checked? and were new plugs used? what gaps were the plugs set to? Should be looking at 0.6 - 0.7 mm
personally i would take it back to who did the work and let them sort it, they know what they have done to the car

NINJA DAVE

Yip all new, i have full support from the garage and there good guys but everybody is scratchin there head just now so i'm checking to see if anyone has had this prob before?

I found a ten yen coin behind the dash when we done the heater matrix and i took it out, since then i've been cursed?!?!?! i'm sure it held the cars "chi" together ha ha ha

ZEN Performance

Have you actually listened for det? Put the knock sensor back where it belongs and test properly.

There are lots of things that could be wrong, and I don't think you have properly eliminated these things.

What boost is it running?
Is the problem boost related?
Is the problem speed related?
What does the engine sound like through det cans?
What is the AFR like?
What do you mean by "all over the place"?


The more info you give, the more likely it is that someone can help. Taking a day to remember the car has only revved to 3000rpm so far isn't helpful!

The engine has been removed, rebuilt and refitted, the ECU hasn't been disturbed, but you're looking at the ECU as causing the problem. Don't you think you're overlooking more obvious potential causes?

Paul

NINJA DAVE

What i'll do is get the mechanic to post the details, i don't have access to the internet at night and unfortunately i have a business to run during the day and i'm not in direct comm. with the garage 24/7, Davey at AWD is working on the car he has advised there is det, he has checked the boost, he has checked the sensors, he has done everything that he knows to do and they all show fine hence we arrived at the possibility of it being the ECU, i was on looking for strange rare occurances that may cause this as the guys working on the car know what there doing and have tried what they can!

I.e sensors failing and not showing flash codes? Any prone to this?
Known ECU faults etc.

Things like this, and i didn't take a day to come up with the 3000mile reply mate as i say i'm a busy guy looking for advice not having huge amounts of knowledge or contact during the day when i do this, i'm replying to posts when i can so if it aint helpfull i apologise!

Proteus

Where abouts are you ?

NINJA DAVE

Dunfermline.....why?

djchriz

Just to add to this I have the very same problem.

The car has had very basic Mods, Exhaust, Induction. Yet when you hit 4000RPM (sometimes 3000) you hit the Fuel Cut Defense.

I had some suggestions of changing the boost control soleniod - Done same prob.

Then Changed the ecu as it wouldn't clear the code 44 - now the code has gone but car still runs bad.

Changed the coil packs and the plugs - still the same.

Now i am loads of money down feeling low and lost at what to do next.

I think we have similar probs.

Jolly Green Monster

iTrader: (4)

what boost is it hitting? sounds like the exhaust has altered the boost control causing it to overboost and hit fuel cut.. can be sorted with a simple bleed valve is that is the case.

Simon

NINJA DAVE

I'm not even getting a code, managed to get a hold of an ECU so will go from there on Saturday and see what happens.

djchriz

It hit 0.7 bar boost at the time, I have tried a bleed valve still nothing, going to take off the dump valve tomorrow and see if that helps.

Any other ideas?

NINJA DAVE

Ok the crank, cam, maf, o2 sensors all checked, all boost components checked, fuel pump etc. checked, had the timing retarding and bad missin above 4000rpm, runs ok on the first boost setting but once you go above it 10-12 psi it starts missin, changed ECU for a Z4 which sorted out the timing but its still missin so i have a Car sparky having a look at the sensors and ECU to determine if there is a wire or resistor fault?

David MY99

check the spark plugs and set the gap to 0.6 mm
This usualy solves the problem of misfiring

NINJA DAVE

Sorry, they have been checked too, the sparky is the last thing getting done then it's going back in to get stripped down and rebuilt.

Scott.T

iTrader: (2)

ignition ignitor, which is mounted on the back of the same bracket where the boost control solenoid mounts ??

NINJA DAVE

ha ha changed the ignitor unit this morning with another, same! Just dropped it of at the electricians a couple of hours ago so i'll know by 4 o'clock if he's had any joy. Here's hoping!

Thank's for all the input folks, appreciate it.

ZEN Performance

I would strongly recommend not stripping the engine before checking the installation of the ancillaries and timing(cam) belt.

For general engine problems post rebuild this is a list of things to be checked, some apply to you, especially checking the cam timing.

First check the coilpacks are installed the correct way around, the front coilpack on each side connects to a white connector, the rear connects to a black connector (or there will be white tape on engine loom for front coilpack). If they are not correct on one side, the engine will run, sound like it's running on 4 cylinders, seem smooth to rev, but have NO power and a slightly strange exhaust note.

Does it spark? (yes in this case)
Does it fire the injector? (check with noid light) (I'm assuming it is, as the first post suggests it's running)

If the answer to both of these is no:
Check the cam timing
Try a different cam and crank sensor
Check ignition switched 12volts is present on one pin a coil pack, and one pin on an the injectors.

If the cam timing is okay, and you are getting power to the injectors and coilpacks, check the cams are installed correctly (ie you don't have the left cams in the righthand head).

Check fuel pressure is correct, leaness caused by injector, regulator or pump problems can cause enough detonation to cause the ECU to retard the timing.

Check the green diagnostic connectors (under dash) are not plugged together, check the black diagnostic connectors are not plugged together.


I very much doubt it is the engine itself (ie shortblock, and heads), or something that will require the heads to be removed from the engine. But there is a lot that comes off and goes back on when building an engine which can be reassembled incorrectly.

Paul

Mark A

iTrader: (1)

Update?

NINJA DAVE

Thanks Paul, sorry i've not been on been really busy with work, mechanically the engine is sound so i wouldn't want to split the heads etc as it would just mean more work, i will work my way through your advice and report back, i really appreciate the help here. The car was going to get scoped by a auto sparky but he did'nt scope it and said it was the plugs and coils, needless to say he didn't get paid as theses have been tried "4" times and he didn't do what he was asked. I'll report back once i get a chance to have a good look, sorry if my posts are missing a lot just i have so much going on in my life just now my head is a mess.

Thanks, Dave G