1987 900S Track Car

[87 n/a]

So I finally got the last piece of the puzzle, an ECU tune for my b202 N/A (thanks Jordan ) and it was time to tackle this install. Some mind-numbing hiccups along the way, like the extraction of the old O2 sensor, guesstimating the CPS gap without feeler gauges, non-functioning relays...

But she is wired up and runs


Real lumpy idle and stalling when coming to a stop though. I don't presently have a tach signal to the gauge. Tried wiring the purple wire in pin 16 on the grey 9000 plug to a blue wire coming from the dash, but still no signal. Anyone have any wisdom to share?

[Jordan]

Not sure which wire is on pin 16 from the grey connector , but it should start at pin #58 from the ECM connector. The blue wire sounds right to the 4-pin dash connector.

[Jordan]

Also, assuming it is connected correctly, make sure the old stuff is disconnected. I had a hell of a time tracking down a no tach situation on the race car until I saw that somebody had plugged back in the ignition amplifier. Disconnect all that stuff.

[87 n/a]

Also, assuming it is connected correctly, make sure the old stuff is disconnected. I had a hell of a time tracking down a no tach situation on the race car until I saw that somebody had plugged back in the ignition amplifier. Disconnect all that stuff.

Ignition amp is definitely out. Traced ECM pin 58 through the grey plug and tried hooking it up to what I thought was the tach lead from the dash. Unsuccessful. Ran out of daylight in the driveway.
I experimented with the idle by disconnecting the AIC valve. Seemed to improve the situation a little.
Was this tune with or without AIC Jordan?

Mind you, this install was all with used parts. Did splurge for a new crank shaft seal though.

[Jordan]

Well the tune was done without and AIC...but then then I enabled its functionality...not sure how it would work. None of our racecars run an AIC, I usually just bump the idle a little by adjusting the throttle plate and it runs super smooth.

[87 n/a]

Sadly, the winter left me with little free time to tinker on my track toy. But now I seem to have problem after problem with getting her to run on T5. Mind you, her initial run was a 110 mile ride down I-95 to home. She blew ungodly amounts of black smoke.

Then at some point maybe 6 weeks ago, I daily drove her to work for a week without issue. Black smoke out the exhaust had seemed to go away and I thought that maybe the ECU had adapted.

Now I am 1 week out from a Performance Driving Event at Daytona and she is fighting me tooth and nail. Spend both this Sunday and the previous Sunday at a gas station 3/4 of a mile from my house with a T5 900 that did not want to start.

She got a new CPS about 3 weeks ago and has ran at idle numerous times in my driveway, but just doesn't want to go any further than 3/4 of a mile.

These are new NGKs with 40 miles on them.


This is how a got home today. A complete stranger in a caged competition drift car towed me.


This is me right now testing relays.


Did finally get the tach hooked up this morning thanks to Jordan's tips. Worked great at idle and on the 3/4 mile ride. Now it doesn't even bounce when I try to crank it over.

I am stressed to say the least. Any wisdom to share from personal experience?

[Crazyswede]

let's forget that this is a custom t5 install and think of it as a stock car with t5 engine management. The system uses the D I cassette, a MAP sensor, throttle position sensor, the CPS, temperature sensor, and an O2 sensor...and intake air...iirc. temp sensors can really wreck havoc in efi. Check or swap in known good coolant and iat sensors. If the car thinks it is 20 below zero it will run rich all the time. Also...assuming you have resistor plugs and the map has a good hose on it?

[87 n/a]

Running resistor plugs.
MAP has its own vacuum line ported just behind throttle body.
But this may be an issue...IAT is zip-tied to top of throttle body, getting an atmospheric reading. Did not think that would matter.
if I should port the IAT, best location? Remember, no turbo. Goes air filter, throttle body, then intake manifold.

[Jordan]

Yeah sounds like a map or temp issue.. You should get the reading off of the main plenum. The air intake temp should be fine reading atmospheric, but if the coolant temp sensor is off , or the wiring is bad then you would have an issue like this. Hook up your CE light and see if you get any flashing lights with the key on, it would help with some basic diagnosis.

[87 n/a]

Got home tonight and had about 15 minutes to tinker before the downpour came.

Relays and spares all tested good last night. The aluminum case ones are 5 prong double-throw relays. The rest are just single-throw relays. Went with the gray plastic single-throw relays tonight. With ignition on, I hear the fuel pump kick on.



Tried another MAP sensor tonight. As you can see in photo below its vacuum line feeds to the intake plenum just aft of the throttle body. The IAT rests on top of the throttle body. Tested the coolant temp sensor between the intake runners and got a resistance reading of 1.77 on the 20K ohm setting. No clue if this is in range, but at least I have continuity.



In the picture below, you can see 4 items from the original 97 9000 harness that are not connected. The large connector is for the rear O2 sensor. The 9000 coolant temp sender (I believe) and I don't remember what the other 2 were for.



I thought the tach was supposed to bounce when I tried to start it??? Not moving now.

Battery does not want to crank it anymore, so I have it out and charging. Can't get her to start . Started at least 6 times in driveway yesterday, but has not started again since it cut-out while coasting to a stop sign yesterday.

New CPS (2 weeks ago), and swapped in new NGKs over the carbonized 40 mile use ones.

[Jordan]

So what are you using for a CPS Trigger? It all depends on how you have the relays set up but the double throw setup is used to activate the 02 sensor pre heater.

Are you getting fuel while it is cranking over?

[87 n/a]

CPS trigger is a 60-2 wheel bolted in place of former A/C pulley. It is a MikeD setup.
When I have the ignition switch flipped on, I can hear the fuel pump on in the trunk and it sounds like the fuel is passing through the FPR at the rail.

[hutch]

Make sure the car is not wired to have the fuel pump run whenever the ignition is on, that could be masking the problem. I saw up the page about setting up the CPS without a feeler gauge, were you ever able to fix that? That could be your problem right there, I can look it up tomorrow or I'd suggest looking what the gap is supposed to be (I think its around .8mm?), but the symptoms sound a lot like a CPS issue to me.

[Jordan]

The pump will prime when the key is on but should stop after a few seconds. Then if it sees a crank signal from the cps it will turn on again. But I'm not sure how your setup is rigged, but that is how it is supposed to happen.

If the pump and or DI are hard wired to the ignition then it is a little harder to diagnose. But they both should be triggered by the cps and not be on all the time.

[johnshan]

This may sound like an obviously dumb suggestion, but you might check that your fuel pressure regulator diaphragm hasn't ruptured. When mine ruptured, it caused a super rich condition that fowled plugs and spewed black smoke. Took me a long time to find the problem, but when I pulled the vacuum line off the reg it was obvious that un-metered fuel was being sucked into the intake. Should be a quick check. It's easy to overlook mechanical problems in the face of overwhelming electrical complexity.