legacycentral bbs

I've noticed the strangest engine behavior now that I've hooked up that new MAP sensor. The MAP sensor is tied into the ecu WITHOUT the aid of a FCD.

Seeing as I have two codes showing up: idle switch and MAP sensor, I found it odd that I was able to boost at all, since the ecu automatically goes into a limp mode/fuel cut when a MAP sensor code is thrown and boost is maintained.

So I decided to do a little experiment.

I ended up turning up my boost controller and seeing whether the ecu would trigger fuel cut at anything above 14 psi. First, I hit 13psi, and sustained it through 3rd and half of 4th. The ecu should cut fuel, correct? NOPE!!

Turned boost up to 14psi. Through 3rd and half of 4th. Bo fuel cut. REALLY strange.

Finally, had the car boosting at 15.5psi!! No fuel cut?!?!?!

Am I missing something here? Is my ecu on its way out?

I have yet to determine whether the ecu is pulling timing with these codes in place, but if it isn't I'll deal with a high idle for more power!! Any ideas?

Uh, dude, that's weird. Maybe your ECU is on its way out... At the least it's gotta be misreading manifold pressure. We need to hook up a Select Monitor to you car.

That's what I was thinking as well. I checked the signal from the MAP. It is working properly. I'm starting to wonder whether all of the codes I've been getting have actually been true. Would the dealer have access to these Select Monitors? I guessing they are even more scarce than the car itself!!

This phenomenon manifested itself back when I first took delivery of the car last year. I was looking at the ecu and noticed that the HKS FCD wasn't even connected to the MAP/ecu!! When I hooked up the FCD in line with the MAP/ecu I got a MAP sensor code. Took it out of the system and I was still able to boost to almost 17psi!!

Does the ecu automatically pull timing and go to conservative maps when it throws a CE code?

Last I checked, none of the DC-metro-area dealers had them (I think I checked with Stohlman, Don Beyer, Farrish, Fitzergald, and the one on Backlick road)... But I have one! :)

Over Thanksgiving maybe we can try scanning them.

I don't know if the ECU automatically goes to base timing and maps if a code is thrown. It does sometimes but maybe not always.

Do you have the part number of your ECU? If it's earlier than 22611AA694, then its code is different from the ones I've been playing with, and maybe it just doesn't have a fuel cut or something.

You have one?!?!?! THAT'S SWEET!! We definitely have to meet over the Thanksgiving weekend!!

As for the timing/maps, I did look at Josh's list of codes and the two failsaves listed were:

1. idle switch - Judges OFF operation (which would explain my high idle)
2. MAP sensor - prevents abnormal supercharging pressure using "fuel cut" in relation to engine load (I'm definitely not getting this result).

The only failsafe that sets base timing/maps is for the knock sensor - sets in regular fuel map and retards ignition timing. I'm keeping my fingers crossed.

Where is the part number located on the ecu. Would I have to take it out the ecu to see it?

You have to take the "failsafe operation" portion of that chart with a grain of salt... Like, it says an IAC valve code will also result in fuel cut, which doesn't really make sense. In my experience, an oxygen sensor code also results in base timing.

On Hitachi ECUs, the part number is on a metallic sticker. When the ECU is mounted in the car, I think that sticker would actually be facing downwards, so it may be possible to contort your body and read the number without pulling the ECU.

It's not hard to pull the ECU, though. Just remove the trim panel above the driver's knees (a bunch of Philips-head screws), then use a 10mm ratchet wrench with a long extension to remove the two nuts securing the ECU in place. Then you have to push the ECU towards the front of the car to disengage the two mounting studs from the holes they're in, and then jiggle the ECU out towards the passenger side of the car. Disconnecting wiring harness connectors may help.

You may want to pull the ECU out so you can take a close look at its connectors... if they look at all dirty or corroded you may want to go over them with some contact cleaner. If you're feeling adventurous, you could put on a grounding strap and pop the ECU open for a look inside, too.

I'll have to take a look when I get home tonight.

One more question. How different are the harness connectors for the turbo legacies compared to the other 90-94 legacies? I saw a few junkyard legacies a couple weekends ago and wanted to take the ecu connectors from their harnesses.

I know the turbo and n/a ecus have different sensor locations in the harnesses, but are the connectors wired in the same fashion? Will I just be able to splice in all of the wires into the n/a harnesses? The reason I ask is because the connections off the wires into the harnesses are getting really loose.

That's what's preventing me from taking the ecu out in the first place. I feel like part of bomb disposal whenever I work under there. I never know when one small move might upset the connections to the ecu.

The connectors are exactly the same. The only difference is which pins are used:

http://www.graphics.cornell.edu/~v/ecupins/

These connectors are of a removable-contact type. Each terminal is crimped onto a wire and then pushed into the yellow connector housing. It's locked in place twice: once by a little plastic tapered lock in the housing and then once again by the big locking tabs that latch onto the entire row of pins. It sounds confusing but will make sense if you look closely at the connectors in person.

It might be best for you to identify which connections seem loose, then to replace those contacts individually. If you grab some ECU connectors from a yard with a foot or so of wire coming off them, you can remove a contact from your car's connector, cut it off, splice in a length of wire with a contact at the end from a junkyard car, and insert the new contact back into your car's connector. Just be sure to get the sizes right (there are two pin sizes)...

I wouldn't worry too much about jiggling stuff in there by hand. Consider what happens when you go over a pothole-laden DC street.

It also may be possible that the weak part is the connector on your ECU itself, rather than the connectors on the harness. One kind of ghetto way of correcting that problem is sometimes to just tin each pin with some solder to add a little more thickness to it.

Well then it looks like I have a a fairly involved project ahead of me.