I have a 1992 4x4 sierra cosworth. Could somebody please tell me where you adjust the co and what level is it allowed to be. At the minute its at about 6.9 and i think it has to be below 3.5.
Thanks.

 

green top saff?

what spec?

 

im not sure of everything, i do know its a t35 turbo and grey injectors.

 

depending on month of first use the car you have may need to be cat tested..

green top saffs (green rocker cover) are closed loop as standard, and should run at less than 1% co at idle(pre cat)

the co is adjustable via the global mod screw on the ecu, but this adjusts the whole fuel table as a percentage, and it is therfore critical to check fuelling on full boost when doing this.

you may well have other faults which are causing your hgh co readings, ect sensor,act sensor, map sensor, air leaks, to name a few common issues

 

Ive been reading other emissions problems on cossies their and the list of problems seem endless. The car starts immediately when cold and sounds okay but if you give her any throttle she sounds like she goes of a cylinder and when you let the throttle off sometimes stops, when she warms up she goes perfect. I thought this was because she was tuned so much and has done this from i bought her about 2 years ago but this is the first MOT for me as i wasnt driving her for a while. I dont want to spend loads of money as i might be selling her. Where would be the most sensible place to start. Could it be a temperature sensor , the temperature hand still reads normal. What is a closed loop system, would this help and how much is it?

 

If not already done so I would put a new temp sensor in, at rear of head, the ECU one, this has nothing whatsoever to do with the temp reading on the gauge, this has it's own sensor.
ECT sensor is available from Matt Lewis 01543 484488, this is the most major component dictating the CO.
Closed loop won't be of any use, it won't cure a fault, and is a much more expensive way of fixing.
Closed loop merely means a loop of inforamtion from the lambda sensor(measures CO) reporting back to ecu, then ecu making any adjustments needed, co read again, adjusted again, and so it goes on, all very quickly though.
Your car fagging out when revved when cold is most likely because it is stinking rich.
I would just put in a new CTS, then adjust the CO to what it should be and see how it is.
The CTS are famous for going potty, and more often than not go super rich when they go wrong.
tabetha

 

closed loop will be of use if its a cat testable car...and if the sensor is faulty the fuelling always goes uber rich.

is the system closed loop enabled?

 

I changed the temp sensor and the air pressure sensor, but the co never moved. The inlet manifold gasket looks new and i sprayed some wd40 around it to see if the revs changed but they didnt. The cars not with me here to check but i checked the tax book and she is actually a 1993. Does this mean there defianately is a lamda sensor and the co has to be below 1. If so where do i go from here? Should i change the lambda sensor?

 

Inquire who made the chip for this car. My guess: with grey injectors the Lambda closed loop is disabled in the chip.
Can you measure the voltage on the lambda sensor?
What happens if you adjust the co-screw on the ecu?

 

The co switch was turned nearly fully clockwise and when i turned it the wee bit more that was left the co went down very slightly, i think. Its hard to tell because it never reads the same everytime and moves up and down when she was on. I dont know what chip it is and dont know where to look for it. The person i bought it off a couple of years ago told me lies about everything on her so no point asking him. I checked on the way home from work and couldnt see any cat on her. I think its a full mongoose exhaust. At the bottom of the down pipe theirs a lambda sensor but theirs only 1 wire from it and when i checked the other threads how to test it they said their was 3 wires so i couldnt check it. The person i bought it of said it had anti lag too but thats probably shit as well.

 

A one-wire lambda-sensor does not have heating.
The one wire that is there carries the signal.
Can you measure that? Should be a signal between 0.1 and 0.8volt, but this one is probably stuck somewhere between 0.8 and 1.2 volt.
What is the voltage on the map sensor signal with key on - engine off and with the engine idling?

 

Ill check both of those tomorrow. Do i still check it from pin 1 and 2 at the brain?

 

Yes.

 

the std lambda sensor on these has three wires,

you can check the signal voltage by putting a mulitimeter between ecu pins 1 + 2 with the engine running, you should see a rise and fall in voltage, i cant imagen a greys chip being closed loop enabled though unless its one of msd`s.

as its a 93 car it will deffo need a cat test, does it have the cats fitted?

 

No cats at all on her. I take it this means i need to find an original exhaust. I went to test the lambda today but i didnt know which pins was which on the ecu as their was no numbers. Ive now the brain home and the chip out and it says on it
B9524XX
NM27C256Q
200
and before all the numbers theirs like a squiggly N.
Can i find out what chip it is from these numbers.
I now know what number the pins are on the ecu as i have it apart so i still need to check the lambda.

 

Numbers are no help at all in finding out who wrote the program or what's in it.
NM27C256Q is the type and model of the chip. 200 is the internal speed.
This is not the normal type for a Sierra 4x4, that takes normally a 27128 eprom (half the size of this one), but if it's programmed correctly that should not be a problem.

I'am not to fond of stage 3 off-the-shelf eproms, especially from an unknown source. Maybe you should consider going back to standard, getting it through the MOT and look around for a reputable tuner that can do a live map for your engine. Sure, it will cost money, but so does blowing an engine.

Back to the problem, I have a question.
Did your car ever run correctly? Did the problem occur suddenly (one day running o.k., the next problems) or did it come gradually?

 

I think it was like this from the start but i didnt know it. When i bought the car i asked to see her start from cold to check for smoke and stuff, she fired up first crack. The seller then told me never drive a cossy cold and leave her running till she is fully warmed. So any time i drove her i let her warm up first, she started perfect and drove perfect as i had her warmed. Then i tried moving her out of the garage a few times without her fully warmed and she sounded like she was off a cylinder and stalled but if i left her alone she usually took over okay. If i hold the revs at about 2000 theres a certain temperature where she changes completely and sounds like she stops missing or comes back on a cylinder again.
I just showed a friend my brain and he said he thinks its from a 2wd because my circuit board is all one piece and not 2 small circuit boards.
He also said just because its registered 93 doesnt mean it needs a cat that the car was probably built in 91 or 92 and to check the silver plate on the front of her.
Ive checked the plate and it says (U) beside exh emission. What does that mean.
Ive also checked pin 1 and 2 at the ECU and i got no voltage no matter whether she was started or not. Unless i done it wrong. I tested the multimeter on the battery first which read 12.52 or something then i put the red to pin 2 and the black to pin 1 and got nothing.

 

Loose the chip and go back to standard.
I can drive my Sierra 4x4 when it's cold, no problem. But that's only a stage 1.
But even a stage 3 should be able to be driven when cold. The Group A's (who also use the grey injectors) and WRC's could be drive cold without a problem.
Very, very, very bad example of an off-the-shelf chip with massive fueling problems when cold. This is why I don't like them.

 

You could have an Escort ecu (P8).
On this page there are pictures of the ecu's: http://www.bigturbo.co.uk/main1.htm

Your alternative is to go to a reputable tuner and buy a new chip for your car - preferably live mapped. You do need to fix the wiring loom and buy a new original Lambda sensor.

 

According to them pictures mine is the first one which is L1 for the 3 door cosworth. it is identical with the yellow mixture screw and all.
Does this mean i need a new brain, new chip and new lambda sensor?
Down the drivers side wing i found a 3 wire plug in a triangular shape with nothing plugged into it. Is this the wire for the lambda sensor?

 

Does this mean i need a new brain, new chip and new lambda sensor?
Yes, to all 3.

 

Emailed stu and he said a chip for an l1 would do as she isnt running of the lambda from that brain anyway.
I then phoned to see what details they needed and someone else said it probably wouldnt work that they would need to set her up that the throttle which and other stuff mightnt match the brain.

 

If you dont have the TPS to match the ECU then no, it wont work. Presumeably you didnt mention that on your E-mail.