Car: '99 on MS-II stand-alone, factory sensors
Symptoms: Engine cranks, won't start.


I picked up Serper3's MS-II. There's a long thread here about a 99 on MS he started.

The MS seems to test out fine on the JimStim. It picks up the cam/crank signals, Megatune displays RPM. The rest of the inputs test out as far as I can tell.

I installed the MS in my car. It cranks, sparks, but will not run.



Some things I noticed:

Throttle position sits at 143%. I went to calibrate it and the value does not change regardless of pedal position.

Middle LED on the MS stays lit, leaving the fans on. Engine temp was 180.

Pulsewidth doesn't change in Megatune. I can hear the fuel pump prime with the key.

Car tachometer does not function.


I don't know where to start. Abe and I were exchanging email as he modifield the MS. He's swamped with studying and work, so I'd prefer not to bug him.

Anybody have ideas?

Thanks

 

do you see RPMs in MT while cranking?

 

Aye.

 

Well, obviously I would have a look at the TPS signal - if you don't get the right throttle position.

If you get (reasonable) rpms while cranking the signals for that seem to be right.

Greets

 

if the throttle is locked at 143%, there's a chance it can be triggering flood clear mode and not injecting any fuel...


for now, set your TPS raw values by hand....then set the flood clear TPS value higher than that....

 

Thanks, I'll try that.

I know the flood clear seems to want a %, while the TPS calibration wants a number. Any easy way to trick this?

 

what happens when you unplug your tps? curious as to why it's doing that.

 

That I don't know. 20 degree weather wasn't a huge motivator to start unplugging stuff

If I get out of work before 10pm I'll give that a shot as well.

 

Absolutely this is it - often I get the same behavior on the stim when I don't turn the throttle **** down.

On the "real time view" or "tune" or whatever it is, you never see the TPS move? You have the OEM ecu out, right?

There's certainly a chance my wiring is suspect, I never got to test it on a car. If you see RPMs, and the "lost sync" guage isn't ticking up (this is important, look for it) then you're ok. But the water temp and the TPS need to be at least ballpark. I'll try to talk you through troubleshooting the harness if you're up for it, it shouldn't be too bad.
-Abe.

P.S.
I would think checking the harness is the main goal. I dunno the wiring, the pin number (though I think I can find out, it should be pin 3E (G/B wire), and it should go to the MS pin 22. Check and make sure these go there. My guess is the +5V isn't getting out right, this would cause issues with both the TPS and the coolant. Look for +5V between pins 26 (vref) and pin 1 (ground). You should see this on the stim, or on the car. You could also check the TPS itself, but I'm not sure which pin is which on there.

 

Calibrating the TPS is easy (with MS-II software!) - there's a "calibrate TPS" menu item somewher eon the far right. You just leave off the gas, hit "set zero" or "set closed" or "get tps value". Then floor it, and get the open value. Hit save or whatever and you should be good - it's obvious once you're on that screen. The number should be changing.

 

That's the thing, the number doesn't change. I'll check out the wiring though.

 

Finally got a chance to take a look at the MS.

The TPS value changes when hooked to the stim. It is pegged at 143% when hooked to the car. Wiring issue?

 

Yeah - this sure seems like a wiring issue! I remember on NA's there was a thing where the OEM TPS would short out, pulling down the TPS, but I don't think that's it in your case. In fact, I think issue is with the 5 volts - when the car sees 5 volts across the sensor, but only 2.5 as it's reference, then it really thinks you're at a way high throttle position.

The issue is trying to figure out what to do about it - and to figure out where all your precious volts are going. Easy things:
Are you getting ~5v when on the stim?
Can you unplug the TPS when on the car, see what happens to the 5 V?
You could watch the voltage on pin 3E as a function of stepping on the gas, see if it changes.

One more thing - please take a look at the harness. There were some very tight things in there - trying to integrate everything compactly, perhaps it got squished at some point, and one wire touches it's neighbor. Give it a quick visual if you can. Along those same lines, with it plugged into the car, measure the resistance between the +5V line and ground, but without the MS on it. Then unplug it from the car and repeat this.

I will go check that I use pin 3E on my own car while you're doing all that. :-)

 

Abe,

I sent a follow up email. I'm getting 4.85V between pins 1 and 26. I was on my back, and go figure, the pins were reversed.

 

According to the wiring diagram, it should be +5V on pin 2I (that's 2i for you fontally challenged people), and yes, 3E is the TPS signal. Again, I'll check my car shortly. but from the earlier email and this info, it should be pin 2I connected to pin 26 on the MS. Also, measuring resistance on the TPS between 3E and 2I should show a difference as you press the gas, even unpowered.

 

Huh. I didn't build that MS, perhaps there's a pullup on the TPS internally? That's kinda a stretch. Plugging and unplugging the TPS at the throttle body is easy, you might as well try it.

 

Unplugged the TPS at the throttle body and it starts.

TPS in megature shows -8.8%

 

It should run, poorly. :-) Huh.. I'm going to have to look at what I did. It shouldn't be that complicated. :-)

 

2I on the car's harness gets 4.85V

3E (TPS signal) stays at 4.85 regardless of actual throttle position.

 

Is that with the sensor plugged back in? :-)