£20 paypal'd to anyone that con figure this out...

[petergoudie]

Any chance your distributor is 180 or 360 degrees out?

Hiya Jon

Changed over 2 sets of known working ht and king leads. Brand new dizzy. Have double grounded the ignitor to the battery And body directly. Also checked out the injector coil pack, got 0.1 ohm on every pin.

Tried again this morning, swapped plugs around and it started after some cranking and "sounded" like was firing on all 4 pots?!?!

Soooooo I get ready to light a cigar and go get drunk, then look down at my wideband (calibrated) and see 16 Afr 3 seconds after starting. Used to be 10-11.

Runs for a min literally then dies!!!!! Arghhhhhhhh!!!!

Same sh#t diffrent day.

Tried to blip the throttle on restart, dies instantly.

Checked the Bosch 044 is feeding the swirl pot, nipping the return line (in tank 340lph in tank feeding 300lph Bosch). Both pumps running. Loads of fuel circulating.

Also tried cleaning the aternator plugs and grounds.

Manifold, head, block and gearbox all grounded. Battery is double grounded.

So now I'm thinking bad loom/map/ECU.

Starts, 15-16 Afr. Runs like a diesel truck for 60 secs.. leans...leans...LEANS... stalls.

New ECU coolant sensor made no diffrence

in open loop makes no difference how high or low the fuel pressure is.

Could the loom have gone bad? (Too much resistance?).

Jon thanks again for helpin me with your thoughts. Genuinely appreciated.

Btw opened up the ECU. Looks like New inside, no weeping capacitors ext. Could a bad loom, lean out the injectors with too much resistance you think?

Will ground the ECU grounds to the body n see if that helps. Only thing I've not tried yet.

Ridiculous me asking to try n solve a prob without even seeing the individual setup, but if anybody can throw somethin out there I've not thought of n get her rich running, there's PayPal beers in the post.

She's not beating me/us... Keep all this good stuff coming!

Thanks!

Chris.

[jondee86]

Also checked out the injector coil pack, got 0.1 ohm on every pin.

This ^^^ does not sound right. I don't have specs for your car but if it uses an injector resistor pack, then it must have low-res injectors. These are usually 2-3 Ohms. The resistor pack puts extra resistance in series with each injector to bring the total resistance up to something like a high-res injector. This means I would expect to measure at least 5 or 6 Ohms across the resistor pack, meaured from the input wire to each of the output wires.

Measuring pin to pin on the output side should give double the resistance i.e. maybe 10-12 Ohms. Please check and confirm ... make sure your meter is on the right scale .

Cheers... jondee86

[Blackcountryboy]

Thanks Jon. Will get one of the leccys at work today to double check for me.

Forgot to say btw I managed to get her to run once long enough to go into closed loop an my WB went to a solid 14.7 AFR so now I'm thinking poss a dud sensor that's used in cold enrichment. Iat is new, along with the coolant sensor.

Thanks again.

Chris

[jondee86]

I'm thinking poss a dud sensor that's used in cold enrichment.

AFAIK the ECU just has the one coolant temperature sensor, and it uses that for all temperature related corrections. Cold enrichment is an important function, so when buying a replacement sensor OEM would be the preferred option to make sure the sensor has the correct output range. Test values for the sensor will be in the service manual.

On cold start I would expect to see AFR's in the high 12's or low 13's. After a few minutes warming up the AFR should start rising, but not hit 14.7 until fully warmed (if it hit it at all). A lot of engines prefer to idle slightly on the rich side... around 14.3. These numbers are just typical numbers off the top of my head .

As an example, when I was running my car without a cold start injector (no cranking enrichment) it would not start on the first or second crank. Only on the third attempt when the two previous attempts had pushed enough fuel into the cylinders to creat a rich enough mixture to fire. Once the engine fired, the cold enrichment would then take over and keep the engine running. Later, I found that a squirt of starting fluid eliminated the need for the first two unsuccessful cranking events.

If your car has a cold start injector, you need to make sure it is working. Later model cars eliminated the cold start injector by getting the ECU to hold the injectors open longer while cranking to create a richer mixture.

Cheers... jondee86

[AE25]

erm, if ecu is compensating for the lean cylinder, will unplugging the oxy sensor put the ecu into closed loop and run off the base map? just don't boost otherwise #2 might turn to swiss cheese.
The pins on a plug could have jumped out, touching enough to give volts but not enough to give good current. maybe check the pins on the #2 injector plug and on the ecu plug.
Any chance you can swap in a known good ecu. could be a dud injector driver or who knows.

[Hiro]

erm, if ecu is compensating for the lean cylinder, will unplugging the oxy sensor put the ecu into closed loop and run off the base map?

Closed-loop is when the ECU is trimming via feedback from the O2 sensor. Open-loop is when it is running purely on the base map.

[Blackcountryboy]

AE25 - Dude, dud injector drivers my other thought. I agree. Wish I could get hold of a spare ECU to test the theory. Only thing is, it "felt" like it managed to fire on all 4 the the other day before it started super lean after, loadsa cranking, just like Jondee said, then leaned n died.

Bought 2x50k ohm resistors off eBay yesterday to splice into the 2 air temp sensors to fool the ECU and see if it starts up rich...

Anybody know apart from the coolant ECU sensor in the water outlet which sensors it uses for cold enrichment?

Also gonna try cranking at 4 bar fuel pressure to see if the open loop afrs move. Will post my findings.

Thanks tons for everyone's replies. Feelin a bit more confident about sorting this.

Chris.

[jondee86]

Will get one of the leccys at work today to double check for me.

Any result on testing the injector resistor pack ?

Cheers... jondee86

[Blackcountryboy]

Hey Jon, sorry yeah, it checked out ok at 11 ohms, I'd got me tester on the wrong setting.

Soooooooo... Bin doin some more reading at work when I should be working and found an old thread off the Mr2oc, dude had v similar spec build to line and exact same situation.... Turned out to be a bad MAP sensor. Had a look on fleabay and even 2nd hand they are £££... So for 30 notes I've just bought a GM 2 bar map sensor (0-5v /power, ground, signal) cos from what I've read they are VERY proportionate to gen 3 3sgte MAP sensor but a fraction of the price. Lil sucker should be here tues. Gonna see what that does. It's the last unknown along with the ECU.

Fingers crossed, will keep you posted.

Nb... Only thing is it disables fuel cut so gonna put my 8 psi wastegate spring in and be VERY careful. If its the MAP, ill get a proper st205 replacement ASAP.

[jondee86]

Yeah... I was looking for a 2 bar Toyota MAP sensor not so long ago, and not a lot of them around. Finally got one from an ST205 for reasonable money, but couldn't calibrate it properly to my aftermarket ECU without a Mityvac pump. So it is a firewall ornament at the moment I'm using the MAP sensor built-in to the ECU for the time being.



Looking at this AC-Delco calibration chart from the interweb, it seems that if the sensor outputs a wrong low voltage, the ECU will see high vacuum (low load) and reduce fuel. A wrong high output voltage and the ECU supplies excess fuel. I would expect the ECU to throw a diagnostic code for open or short circuit.

The coolant temperature is the major input for cold enrichment. There is some compensation for IAT but it is minor compared to the water temp enrichment.

Cheers... jondee86

[DX20VT]

Doesn't the 3SGTE have an AFM as well as a map sensor? What car is it in?

[jondee86]

What car is it in?

From an earlier thread "st205 gt four".

Cheers... jondee86

[Blackcountryboy]

Hey Jon sorry for the late reply. That GM map tables most appreciated.

Tested my coolant sensor across the pins. 3k.

Tested at the ECU plug (THW - green wire, middle plug, top row no 5 pin) against the brown e2 pin.... NOTHING???????

Battery disconnected. Shouldn't it be 3k at the ECU pins too??????

Anyone tell me if I've messed up?

Thanks again.

Chris

[jondee86]

With the plug out of the ECU and the plug on the sensor, you should get essentially the same (3kOhm) reading when testing between THW and E2 pins on the ECU plug. If you don't, then you have a continuity problem.

You need to test the green wire end to end and the same with the brown wire. If you have some of those test wires with an alligater clip on each end, figure out a way of getting one probe connected to the pin in the ECU plug and the other probe to the pin in the sensor plug. You should measure no more than a one or two Ohms. If the reading is very high (OL or infinity), look for a break in the wire.

If you test between the wires and ground, you should also get OL or infinity. If you get a low reading, then you have a short to ground and need to look for a place where the insulation might have worn down on a sharp edge allowing the copper to touch ground on the chassis.

Cheers... jondee86

[Blackcountryboy]

Hiya Jon, did as you said dude. Coolant sensor wiring checks out ok. Got 4.98v at the plug with the ignition on.

Tested the map too. 5v feed ok. 2.30v (0 psi) from the signal wire with the ignition on and engine off.

With contact cleaner I cleaned every plug and double checked all the grounds.

Turned the fuel pressure upto 4 bar.

After lots of cranking she fired up, ran rough, but revved ok to 2-3k!!! She eventually died tho and wouldn't restart. Sounded like she was running on all 4 pots tho.

Ok... So I double checked the plug gap. 0.8mm.

I'm running Ross 9:1 forged pistons. Accilite rings tapped at 18/20 thou (top/middle rings)

I've heard that Ross and Arias spec 9:1 using a stock 1.4mm hg? Mines a 1mm cosmetic. When I bought the head, complete with JUN valves second hand (had it checked over and rebuilt professionally) the dude said it had a v light skim but didn't say how much. Done some research and I guesstimate the build to be at least 9.3:1 ..... Could I be blowing out the spark, even with new platinium plugs, leads, cap, rotor,, coil?

She "tries" to catch and start. Reads 15:1 when she does start. Goes off the scale 35:1...(pig rich?) When revved warmish.

Tried tapping the plugs at 0.7mm a while back, also used new 6s and 7s heat range wise but made little difference.

Does any of this make sense to anyone??? Any ideas anyone's got no matter how small are appreciated.

Bin to Napkin. Got some 1/2/3/4/5k resistors to play with tmrw on the coolant sensor, on the reasoning she seems to start better with more fuel pressure and reads 15:1 when I'm looking for 11:1 cold. 13:1 warm at idle.

also...

16 hg at idle. 3sge (9.8/252) intake retarded 4 degrees. HKS (9.0/256) exh advanced 4 degrees (To raise vac and reduce overlap to get her to idle).

Idled ok ish today, is just a swine to start!!!

Thoughts peeps? I'm thinking more fuel... Even tho plugs are black...

Thanks

Chris