jaytc2003

iTrader: (1)

Hello, new to this and also scooby ownership so please bare with me.
Got myself a 1992 scoob import (MY92 I believe, please correct me if I am wrong), advertised as a WRX but think it is just a normal turbo.

Are you ready? bit of a long post.....

It has a few mods, like a blitz exhaust from the cat back, a blitz induction kit, and also a dump valve (a dump to air - think this again is blitz but may be HKS)
The problem I have is at times the car basically doesnt want to rev past 4500 this can happen in any gear. When I get to that rev range the car rapidly slows down on the acceleration so if I am overtaking it can cause a lot of concern. This is quite erratic and at other times the car pulls through cleanly up to the redline 7000rpm

I have read a few posts on here, some with similar problems but there I cant see a definitive answer. I know it would be hard to say exactly what it could be, but some ideas for me to look at would be a start.
MAF keeps appearing, what does this mean? Where can I find this in the engine bay? Is it near where the induction kit will be?

The car I have been told was always run on super unleaded // Optimax and I have used this myself and also some lead free octane booster so I dont think it is a fuel issue.

Can anyone advise me on some possible suggestions?
Changing the subject slightly, I will be looking at getting a few more mods soon once this running problem is sorted. I keep seeing the AFC and Defender being mention, what do they do? Also what other mods would be recommended.

Finally (told you it was a long post) I have 2 companies nearby me that specialize in jap performance cars, these are DP motorsport in warrington, and Hiteq nr Wigan. Does anyone know if these companies are okay, and if not any other companies around the gtr manchester area?

thanks for any help

axgt_bwaii

iTrader: (6)

for a start id do a ecu reset and go from there. i have a 93wrx.

to do this the easy way just dissconect the battery for an hour. the ecu will forget any hiccups/faults it may have recorded and its memory will be clear. sometimes too many ecu faults can cause the car to run in safe mode or just ****e in general. once connacted again drive the car normal, let it warm up then take it for a resonably hard drive. dont thrash the **** off it but give it some. if theres anything wrong you should get a check engine light come up!

try that and tell us how you get on.

jaytc2003

iTrader: (1)

Would I not get this light coming on anyway even before I do a reset?

axgt_bwaii

iTrader: (6)

id depends on whats causing the problem. ive had a few ecu codes come up. some come on and dissapear after 10 or so seconds. others will stay on till the car has been switched off. if the previous owner had lots of faults the car can perform badly. when i got my wrx there was about 5 diffirent ecu code faults. the car was giving me juddering on boost (sometimes) but as far as the ecu codes go the car should not of even started. i think it came up with maf, lambda and some other major ones. just reset it m8 honest its a good way to start. its free, easy to do and clears your ecu.

dj219957

Some pointers for you mate.

Check your coil packs. These break down over time and crack. If there are cracks in the tips they short to the block causing missing. Shows at 4k plus rpm.

Check the dump valve is plumped correclty and that there are no splits or leaks. If you can put the standard one back on.

Check the boost pipes (there is a little cyclinder on the drivers side suspension turent with some pipes coming from it) follow the pipes to the actuator, turbo inlet and air box. Again look for leaks or cracks or botched plumping.

The induction kit you have on could be the problem. If you can put the standard box back on. It could have damaged the maf. not a likley one though

When you say it runs bad past 4k do you mean the car violently stops or just that the performance falls off and the car misses? If it is a voilent stop then this is overboost. If it misses it could be maf, or coil packs or summot else.

Im not an expert at all but there are a few things for you to check there.

Andy

tath

check all the jubilees past the turbo are tight and there are no leaks anywhere - mine did this (erratic performance past 4k) and it turned out that someone had forgotten to tighten a jubilee from the intercooler ( ) and the boost was forcing the hose off a bit then it was popping back on under vac

jaytc2003

iTrader: (1)

When I say that it runs bad, it basically stops accelerating as though the engine has cut out even though it is still running (if that makes sense) I have noticed that the boost does drop off when it happens but I suppose as It is no longer accelerating at a fast rate that would be expected.

What does MAF stand for? and where exactly is is? is it attached to the induction kit?
Also the coils, where are these located. Not really had a good look around the car yet.
Thanks for the pointers will have a check of all pipework and will also check my boost gauge when at max to see what that reads. What should my max boost be on a MY92 import?
Will let you all know how I get on

dj219957

Sounds like its overboosting. It should boost MAX to 11 ish psi. Check your boost plumping. The exhaust could also be the cause, people have said that some types of decat down pipes cause overboost. Although my full decat is fine

vulnax999

iTrader: (7)

MAF ( Mass Air Flow meter) is the short black hard plastic pipe with an electrical plug near the top middle of that pipe, in the pipework from air box / air filter in the induction kit, near the o/side wing. If these get damaged / fail it can lead to engine damage. ( Engine can run weak / lean and damage pistons, maybe bearings ).
A fuel cut defender lifts the point where the ECU cuts the fuel to save the engine, so allows you to raise the allowed boost .. but too much will blow it up especially not mapped for it!
PFC is an Apex'i Power Full Computer, a replacement full ECU that is programmable to match your current mods, and make full use of them safely.

Coil packs, if you have a car with these on ( at the age you say your car is, it IS likely you do! then these sit on top of each of your plugs, as each is an ignition coil per plug instead of a central coil with 4 high tension plug leads to the plugs. If these become brittle with age and heat they can fail, earth to block ( so misfire ) and also lose spark power with age. Worse at higher boost.

When you lose power at 4000 rpm plus, does it stop like you hit a brick wall, or just surge on and off , or stick at 4000 rpm and low boost ( 0.5 to 0.7 bar, 7 - 9 psi ) ?

First is fuel cut as your boost is over what the ECU will allow ( usually around 17 psi though ); second idea is perhaps MAF, or plugs/coil packs if running highish boost or not had plugs changed for a while ( 2 years, 20000 miles +) or changed recently and coil packs were disturbed and now are failing; third idea is the car's engine has problems, the ECU puts it into limp home mode, low revs and low boost allowed.

Dunno if that helps, hope so and you get car sorted soon!
Have you and ECU mods fitted - superchip, Scoobyecu, Unichip, VOSchip, etc?



Ohh yeah, avoid vent to atmosphere dump valves, they don't help performance!


Overall is sounds like your car's ECU is going into limp home mode, dueto some problem, likely a sensor.

jaytc2003

iTrader: (1)

thanks for your indepth suggestions there vulnax999, much appreciated. Driving to work today I think it is more likely an overboosting situation as it happened once today. When I get to the specified rpm whilst using full throttle it just surges on and off sort of a splutter, if I use part throttle at that rev range then it will pull through to over 6000rpm. I have a blitz boost gauge in the cockpit (sound like a pilot - suppose driving one of these things though!!) and it goes upto to 1.5 bar on the boost gauge and when my car comes on full boost it is over the 1 bar (14psi I think) so could be that.

If it is overboosting then is there anything that you would suggest I check? Something as simple as pipework or could it be a weak actuator (dont know if this turbo has one as totally not familiar with this type of car)?

How come Vent to Atmo dump valves hurt performance?
Any more suggestions would be appreciated.

jaytc2003

iTrader: (1)

Have you any ECU mods fitted - superchip, Scoobyecu, Unichip, VOSchip, etc?

How would I check my ECU? where is that likely to be located?

Thanks again

stevebt

iTrader: (8)

i have exactly the same fault on mine, the car dies at about 4000rpm ish in every gear and its definately the MAF on mine

vulnax999

iTrader: (7)

ECU is under the carpet in passenger footwell, under a large metal plate held down by about 5 screws/bolts. The ECU is screwed down under there, and then needs 4 screws removing from it's sides to reveal the circuit board. If there is something plugged into a socket in there, or other strange wires beyond the main 3 or 4 from the car wiring loom, then an additonal board is fitted. It could also be something fitted up-stream in the wiring loom, ( such as a fuel cut defender or superchip, or boost controller ) though.

VTA dump valves let air that has been measured by the MAF to be released to atmosphere when it is not needed, like on lift off the throttle, so the ECU thinks more air is in the inlet system than there really is ( the recirculating dump valve puts this spare air BACK into the inlet ! ). So the ECU adds more fuel, and then runs richer, loses a little power perhaps, has higher emissions and fuel consumption, and may well pop and bang and even flame from the exhaust depending how bad it is!

The recirc type maintain the proper air to fuel ratio as the measured air is still there and so fuel can be better matched in the right ratio!


If you are near any specialists may be take it into there for an ECU error code read out, and see if MAF is dead, or lambda, ??

jaytc2003

iTrader: (1)

I am in Tyldesley, Gtr MAnchester about 15 mins from DP motorsport in Warrington, are they reputable or is there someone else who is recommened?

tath

i've heard good things about DP, and yet to hear anything bad if that helps...

jaytc2003

iTrader: (1)

Well did the diagnostics ECU check and no codes came up. Then I reset the ECU took the car for a test drive without caning it until the check engine light was flashing steady. Disconnected the connectors and then went for another test run giving it a bit of stick and it hasnt stuttered once. Hopefully it is cured, yeah!