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The mkiv Supra Owners Club

Its ALIVE..well sort of


Odin

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As some of you may know i have been doing an n/a-tt transplant for the last 3-4 weeks and have been experiencing some difficulties,to cut a long story short i rewired the lambda sensor today and swapped over the 2 identical black wires(this was on the exhaust part where there are 2xblack/1xwhite/1xblue) and connected them properly to the mating half of the stock lambda sensor (the part which runs into the loom) and hey presto it worked!!i reset the ecu and checked for diagnostic codes and there werent any - Winner!...

Obviously i decided to take it for a nice drive to make sure everything was ok,i started on country lanes and progressed onto the M6 and everything seemed great she was running really well the turbo's were boosting perfectly - if anything the 2nd turbo was kicking in a little late at 4500revs but all in all a very impressive drive,its set to 1 bar and didnt exceed that and the oil temp never went above 100 degrees,....

However after about an hour or so there was a kind of missfire - almost like a fuel cut or something to that effect,at first it was happening when the 2nd turbo should be kicking in but now its happening just driving it normally even down my road at a slow speed. - The main symptom is all of a sudden i will lose power on the throttle pedal for 1 approx 1 second and then it will quickly kick back in as if it had never lost power which means a massive jerk/surge in acceleration, so once again im having what i hope will be my final teething problem with this project for a while and was wondering if anyone had experienced anything similar? ps i checked all the turbo pipes and they are all still on and there are still no diagnostic codes showing :)

 

Many thanks as Always

 

James

 

(just to give a special thanks to all that have helped me this far including RyanG,Chris Wilson,KenBlockSeal and many others - Thanks a lot guys much appreciated)

Edited by Odin (see edit history)
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Grrr in addition to this i got home today and tried to take a reading from the diagnostics and now for some reason i cannot get one :( also i checked the wires to see if any had been incinerated but there is no evidence of this the coilpacks all seem fine,I started it up after all these checks and it idled for about 30 secs before it just cut out,now it wont start-it ignites but cuts out instantly,this made me question the fuel level as i had an auto tt rev cluster fitted to an n/a so i thought perhaps the fuel gauge was incorrect (if thats possible) i dropped a nut on some string into the tank and there was some fuel in it (the fuel went to 1.5" above the nut) So now i have it a brick wall ive gone from a great runner to a non runner in about 2hours worth of driving .. Any ideas?

Many thanks

James

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I have been unable to locate these earth wires under the intake manifold is there a reference near to where they bolt on Chris? Trying to find it on my driveway is proving more difficult than anticipated i should have left it at the garage.

It is strange though on sunday it started every time and now i cannot get any diagnostic codes for it and it wont start it all now - as soon as it ignites it cuts out :(

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It seems like either a fuel or ignition problem but it's probably something as simple as a faulty/loose connection next time I think of doing something like this I think I'll leave it to the experts :D just wondering if there was anyone in the cheshire area who may be able to look it over for me?

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Ok Chris after further inspection and removing 2hoses temporarily I can see that there are no earths on that housing under the intake manifold (providing I'm looking in the correct place?approx 3" below and 2" to the right of diagnostics port) which leaves me a problem,where have these earths gone and where else are they supposed to attach?

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The thought is getting very tempting i possibly have access to a trailer and winch i would have to see how much it would cost me and save a bit though, - On the plus side i did just manage to get a diagnostic code which is showing as 78 - apparently some sort of problem with either the fuel pump (which is a stock n/a incidentally) or the fuel pump circuit, - Apart from the obvious - buy tt a fuel pump,is there anything else that may be causing this. Im wondering whether in my excitement to get the car out i have managed to fry a fuel connection wire around the gearbox as it did get rather hot down there and i didnt put the wiring in silicone hoses,

I also dont think that there is any power to the pump as i cant hear the humming noise of it priming even when i bridge +B and FP in the diagnostic port which makes me think its more a connection than the pump itself.

Has anyone ever encountered error code 78? if so what did they try? I have ran a search and looked through the 14pages but couldnt see anyone having had this problem

Many thanks guys

Edited by Odin (see edit history)
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DTC 78 - FUEL PUMP CONTROL CIRCUIT

CAUTION: If ECM replacement is instructed in following testing,

always ensure ECM connectors and ground circuit are okay. If

either are suspect, repair and repeat testing to confirm ECM

malfunction.

Circuit Description

The 2-speed fuel pump is operated by the fuel pump ECU which

receives a signal from ECM to compensate fuel pressure for start,

light engine load or high engine load. DTC is set during the following

3 conditions:

1) Open or short in fuel pump circut is detected for 1 second

or more with engine speed of 1000 RPM or less.

2) Open in input circuit of fuel pump ECU with engine speed of

1000 RPM or less.

3) Open or short in fuel pump ECU diagnostic signal line with

engine speed of 1000 RPM or less.

Possible causes for all conditions are:

* Fuel pump ECU open or short circuit.

* Fuel pump ECU.

* ECM power supply circuit.

* Fuel pump.

* ECM.

Diagnosis & Repair

1) Turn ignition on. Using jumper wire, connect DLC1

terminals +B and FP. See Fig. 11. Check if fuel pressure can be felt

in hose to fuel filter. If pressure is felt, go to next step. If

pressure cannot be felt, go to step 3).

2) Check for open or short in +B and FP circuits between DLC1

and fuel pump ECU. Fuel pump ECU is located back of left rear

wheelwell, behind trim panel. See appropriate wiring diagram in L -

WIRING DIAGRAMS article. Repaire as necessary. If circuits are okay,

go to step 5).

3) Ensure ignition is on. Using DVOM, measure voltage between

ground and DLC1 terminal +B. If voltage is 9-14 volts, go to next

step. If voltage is not 9-14 volts, inspect ECM power supply circuit

and +B circuit between DLC1 connector and main relay. See appropriate

wiring diagram in L - WIRING DIAGRAMS article. Repair as necessary.

4) Inspect FP circuit for open or short between DLC1 connector, fuel pump and ground. Repair as necessary. If circuit is

okay, replace fuel pump.

5) Access fuel pump ECU. Fuel pump ECU is located back of

left rear wheelwell, behind trim panel. Disconnect fuel pump ECU

connector. Check voltage between terminals "E" and FPC at ECU wiring

harness connector. See Fig. 18. Turn ignition switch to START

position. If voltage is 4.5-5.5 volts, replace fuel pump ECU. If

voltage is not 4.5-5.5 volts, go to next step.

6) Inspect FPC circuit between ECM and fuel pump ECU for

open. See appropriate wiring diagram in L - WIRING DIAGRAMS article.

Repair as necessary. If circuit is okay, inspect "E" circuit between

fuel pump ECU and ground. Repair as necessary. If both circuits are

okay, go to next step.

7) Inspect DI circuit between ECM and fuel pump ECU for open

or short. See appropriate wiring diagram in L - WIRING DIAGRAMS

article. Repair as necessary. If circuit is okay, replace ECM and

retest

pompatest.JPG

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