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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I drove my car to my mates work place, car was nearly empty of petrol, he works as a mechanic for a truck and lorry place.
We did brake test and then emissions test, it passed on tick over but failed on fast idle, so drove home to get my bits and filled up on same shell optimax fuel and came back. I did my brakes and then changed my ECU chip for the standard one and cleaned the lambda probe and let the car heat up. We then re did the emission test and it passed on idle and failed again on fast idle but this time it was worse??

Anyone know why???
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john 33_16v · Posted: Tue Aug 05, 2008 5:55 pm Post subject:

Hi Al,

I'd be tempted to try a brand new Bosch lambda.

Cheers,

John
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Lambda sensor was new last mot and car has not done many miles, I hope it’s not that as they are v expensive.
Today when I started the car from cold, it started ok but didn’t like to rev and smells like it’s over fuelling.
I removed the lambda out of the equation by telling ecu there is no lambda and disconnecting it and it still did the same. The lambda is working on idle when warm, you can hear it changing the fuel mixture as per normal.
I will try with up rated chip and or another ecu I think.
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I undid the 5 min AFM mod today, I will see in the morning, with a cold start, if its made any difference and then possibly try another emission test with a few different ecu's if not.
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Last night we tried again with another standard ecu and still got 0.59 - 0.61 ish on fast idle at 4k afer a drive. Boy did i not like holding 4k and stopped when temp gauge got to 100 ish, even though the warning light didnt come on.

I started it this morning from cold, with a different standard ecu and it didnt fast idle. I put in another chipped ecu and it idled fine and fast idled and drove ok??? I cant remember which one now, as i have a few to play with.

I'm thinking that the normal ecu gets its engine temp from the coolant temp sensor "CTS" and the chipped ECU gets it from somewhere else. Could the chip just tell the ECU that the engine is colder than it actually is, therfore putting more fuel in, along with a slightly different map?

Does anyone know what the resistance should be at cold and at normal running temps, the motronics data sheet only talks about a 5v referance value and mentions no range form cold to normal running temp. I was thinking of putting in a resistor for the time being as its using loads of fuel now.

I tested the CTS with a voltimeter on resistance and got no reading when at normal running temp or when cold and there was no short, so i think its dead.
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Admin · Posted: Fri Aug 08, 2008 5:47 pm Post subject:

Hi

I would very much doubt that the chip does anything like take a different source for the engine temp. Should just be a different map.

All the best

Keith
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Just a coincidence that the sensor went at the same time I swapped the chip, i hate things like that, hard to diagnose. Or maybe the CTS went ages ago and the chip i have was sooo good it didnt need it Laughing

and when i put it back to standard it highlighted the problem Laughing

I assume that a failed sensor is seen as no signal and equates to an engine always cold state?
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Admin · Posted: Fri Aug 08, 2008 10:20 pm Post subject:

Hi

Possibly, or possibly it just defaults to a guessed temperature.

All the best

Keith
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

What I can’t figure out is that when the engine IS cold it runs bad on fast idle with standard chip but not another? If a CTS fail is guessed temp you would think that guessed temp would be close to a cold temp or car wouldn’t start. Mine starts fine and idles "I always start with no throttle as you should" but anything other that closed throttle position, it stutters.
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I wish someone answered this before I bought a new sensor

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Need help understanding the 5 min AFM mod.
The engine at a set rpm will draw in required amount of air (a)
The flap is set at a set resistance (r)
If you alter (r) to be lower, the same amount of air is going in, albeit at a slower rate, as the engine only sucks in what it wants but the flap position opens further, telling the ecu that more air is going in and so puts more fuel in.
I would assume this is true for the opposite, as in if (r) is increased then the same amount of air is being sucked in but at a higher rate as the flap position is restricted, telling the ecu that less air is going in so decreases the fuel.
How come when I had a play around with my flap, trying to put it back to original, I realised that I had increased (r) and definitely got better torque, ect ect?
The person who marked the toothed wheel prior to me owning the car had indeed loosened it, if he used the reference point of where the w clip holds the tooth in place. I put it back to normal reference point but it got better the more I tightened it?? Embarassed

HELP!!!
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Admin · Posted: Tue Aug 12, 2008 10:23 am Post subject:

Hi

I would guess that for some other reason the engine is running too rich, and adjusting the afm is just reducing that richness.

All the best

Keith
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Just had a thought, if the CTS had failed the car wouldn’t start. I tried with it removed and it didn't. One of the terminals had a bit of corrosion on it though and when the car is running whilst warming up if you remove it there is a definite change in engine tone, but no change when hot???
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I changed the AFM for a non opened one and didnt tune it for idle " remove cat and adjust idle mixture screw" and on fast idle at 2k - 3k the emissions were .23 - .30. So it should pass if i put a bottle of injector cleaner in it and set the idle properly as its a bit rich.
The manual says if changing an ECU or AFM then you need to set idle with lambda disconnected, i guess it needs a good reference point.
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

well i tried with an unopened AFM, everything but the CO is good, so lambda is working, cat is working, its just over fueling!! Arghhh!!
mechanic says changing the cat wont help as its doing its job, lambda is working and high fuel pressure shouldnt make that much of a difference.
I have set the timing "dizzy cap" to standard, made no difference, tried virgin AFM, slight difference, cleaned the lambda sensor, how else can i get over fueling down??
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paulhide · Posted: Thu Sep 04, 2008 9:48 am Post subject:

Listening to the radio won't help. Very Happy

Try lower grade fuel??
Better plugs?
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

better fuel grade is supposed to give a cleaner burn, plugs are the correct platinum for cat 33 and looked fine when head was off.
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Admin · Posted: Fri Sep 05, 2008 1:08 pm Post subject:

Hi

Check carefully for any air leaks in the exhaust. Air getting in there can register as a weak mixture via the lambda probe, hence triggering the ECU to richen the mixture.

All the best

Keith
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

thanks for the suggestion keith, I have new gaskets all round, I am at a loss Crying or Very sad

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john 33_16v · Posted: Fri Sep 05, 2008 2:40 pm Post subject:

Al,

has your car got standard injectors?

Just a thought that some previous owner might have put in bigger (vauxhall carlton??) injectors to try and get more power.

Think the bigger ones are brown. Standard are yellow.

John
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If it aint broke, fiddle with it until it is!
- - - - - - - - - - - - - -
93 33 16v Mirtle Met
08 Fiat Grande Punto Exotica Red
90 Yamaha FZR600 Genesis- Silky white/red/blue

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

Mine are standard yellow ones. It must be, bad map, high fuel pressure, leaking injector or Lambda sensor.
I will try with another ECU when i get a chance, then get injectors checked and at a last resort get a lambda sensor, unless anyone else can think of anything.
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ZeNiTh-PbArM · Posted: Sat Sep 06, 2008 1:01 am Post subject:

hi, do you get some blink codes from ECU? if no i'd replace lambda sensor as a likely culprit with OEM unit.
regards,
zp

BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

I should be getting it on an alfa diagnostics on Tuesday to check everything. Can you diagnose a sticky injector by removing HT lead and injector wires for each cylinder 1 at a time and run emission test?
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

well i took it back to the alfa garrage but he didnt want to put it on the diagnostics saying that you cant see the advance readout! I have seen this last time i had it on one of those things and it also showed the lambda readout. I guess i will have to make up some kind of connection and connect it to the lambda connection to get a read out but whilst on the emission tester it said it was ok, not sure how good they are??
I havent replaced the lambda sensor as they are pritty expensive, i will do as a last resort, but even when it was new i still had problems.
Disconnecting the fuel relay type device, so it thinks its running on 97 ron fuel "which it is" does make a difference, the timing is advanced and it does accelerate harder.
I was thinking of changing the coil???
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BigAl · P4 Joined: 06 May 2003 Posts: 2995 Location: U.K Surrey

does anyone else have problems with emissions on the 16v's? my first red 16v would fail on fast idle but it was allowed a faster idle and it passed. I have always had problems with my silver one.
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