Ok, I can check out the rats nest. That is going to have to be a weekend project.

How did you fix yours? Was it an electrical routing problem, or was it a tube routing problem? I am assuming it was an electrical routing problem, since I don't think the ECU could figure out if the tubes were connected wrong.

Before I check my ignition stuff, is there actually a way that I could have it connected wrong so that it would run fine under partial throttle and then stop running during low RPM boost? Seems like timing and ignition don't fit that problem description. I checked the plug wires and they are going to the right spots. I didn't disconnect the coil harnass; I only plugged and unplugged the master connector so I am not sure how i could have bunged that.

 

Yes, you can cross up the white and blue ignition harness connectors which throw the timing off. It causes the car to buck when trying to boost (or just apply quick load) but will idle ok. Also make sure you didn't mix up the fuel thermosensor and the coolant thermosensor connectors. They are the same connector and can be easily exchanged (but have two distinct responsibilities).

 

Also check for a bad leading coil. The past two cars I had in had a bad leading coil pack.

Swap it with a known good one or if it is orginal, get a new one. Last car I had in the leading coil was so weak that it created all sorts of issues at all RPMs.

Definately check that you did not mix the trailing coil wires up. If they are backwards, you can pop the engine real quick.

 

Well my problem was there were so many wires eliminated that it was throwing a million codes. I lookked it up and people have installed resistors in the past but I just purchased a PfC and that took care of that. I would just look over the wiring seeing as you didnt modify your harness.

 

Yeah, no codes for me. It is such an abrupt transition so i really don't understand why the ECU would do it.

I am going to build one of the new data logger things in the forums right now and am hoping it will give me some insight as to which sensor isn't right.

 

Did you ever figure this out?

 

No, still in the process of building that datalogger. The car is now in storage (and ran great on the way there so long as I didnt boost AT ALL - same problem), so I plan to go and try this next tuesday (1 week+two days).

 

Did you try swapping out the leading coilpack?

 

had a similar problem with a Sequential deleted car.. check to make sure that your Fuel temp plug and the coolant temp plug are not swapped.. they are both green plugs and the same shape. the plug that comes from the harness thats closest to the Two primary injector plugs goes to the coolant temp switch. hope that helps

 

Ok,

So I finally am able to work on this. I made the super sweet ECU data interface, and I now have a better idea of what is going on.

My coolant temp and fuel temp sensors appear to be reading correctly.

My throttle position sensor is a tiny bit off at idle, but really not much. It is in range at full throttle.

Here is the kicker:
When I am under 4000 RPM and floor it, the car goes SILENT. No combustion whatsoever. This occurs immediately when I cross the 0 PSI mark. It is very odd. I can back out of the throttle and the car snaps right back to life. Looking at data from the ECU, the ignition degrees goes to like -10, and the injector pulsewidth almost triples. These seem like they are normal values, and what they should be. Without being able to actually test if the car is sparking while driving, I assume that the ECU is sending the right signals.

When I am ABOVE 4000 RPM, I can floor it and the car takes OFF. Just like normal, and pulling 10 PSI. There may be something up with the car at higher RPM as the boost peters off, but the fact that there is this startling difference above and below 4,000 rpm is what is curious.

I am working on this currently, so speedy replies are much appreciated. Thanks!

 

Ok, sitting in my car now. The car seems to not actually pull 10 psi if I am in 2nd and floor it. It does pull some boost though (3-5 psi).

I grabbed more data for the higher RPM stuff. When under boost at high rpm, the car is at around 40-50 degrees of advance on both coils. Tooling along, it is more like 25 degrees (at lower rpm). When the car doesn't run, the advance reads out as like 10 degrees or something.

Does that help at all? As the fuel seems like an odd thing to have not work, maybe this is a spark problem?

Thanks

 

Leading coil pack.

 

One thing I did forget to mention: there is a small box behind the ECU that I have no idea what it is. It appears that two connectors possibly plug in to it, but I can't for the life of me figure out which connector to plug in to it or what it is. I think on automatic cars one of these connectors goes to a transmission control box, but I have a MT and only have one box.

The car seemed to run fine with either or no connectors plugged in to that thing so I left it unplugged I think.

 

Ok, how do I test said leading coil pack?

 

Just tested the leading coil as per the manual - 0.4 ohms for the primary winding and 13.5 k ohms for the secondary coil windings.

Does it matter which leading plug wire goes to which plug?

 

I just ran a quick test.

I unplugged the leading wires and tested the car. Same symptoms.

I also unplugged the trailing coils and drove the car. Exact same symptoms, but this time I could see TONS of arcing through the plug wire and at the end of the plug wire. It was snapping loudly!

I don't know if this proves/disproves the leading coil theory or not, but it is more info.

 

How many miles does the leading coil pack have on it? The last three cars I had in here had bad leading coil packs, they test fine but are weak. You will notice it more under boost because the spark is so weak.

Not 100% sure this is your issue but when they are bad, the car will run like crap under load and boost.

What I do is I have a spare ignition harness and a known good leading coil and two second gen plug wires and rig it so i can bypass the oil under the plenum for testing purposes.

 

I honestly don't know how many miles are on the leading pack. However, I do know the car was working just fine when I took it apart (yeah, I know that means it is my fault).

If the coils were bad, wouldn't they not pass the ohm tests? I am amazed at how silent the car is when I cause the problem below that 4000 RPM. The car completely and utterly dies. No bucking, no nothing. It seems that with a bad coil pack (that was good enough to run the car at all when the trailing coils were unplugged) would cause at least SOME sort of combustion. That said, for the problem to be on both rotors you would think that it would have to involve some common piece of equipment. The ECU and the leading coil pack are the only things that are common!

When I removed the wires from the leading plugs I was able to get a spark going (with a screwdriver) over 1/4 inch, probably closer to a half inch. I didn't have a spark tester, and I have no idea if this is good or not for for these coils. The trailing coils seemed to have more power, but I have no way of quantifying it.

What is the oil under the plenum you talk about? I am a little confused about what oil you would have to deal with to test using a spare coil pack. Also, what is different about the Gen 2 wires?

 

do you have L1 going to the front lower and L2 going to the rear lower???

how old are the plugs?

 

I do have L1 going to the front lower and L2 going to the rear lower.

The plugs are new after the rebuild. They were new at the rebuild and around 150 miles on them.

David

 

OK, so, new info:

I bought a Power FC so I could see sensor values better and know for sure that the ECU wasn't in limp home mode. I was hoping a little that it might just fix the problem. No dice.

Now with the Power FC installed the car does the exact same thing as before, which is cutting out COMPLETELY at low (below 3500 ish) when hitting 0 PSI (coming out of Vacuum). No sensors look like they are going wacky.

In addition, when learning the idle the car idled for 10 minutes and then died. The car will now not idle for crap, and will not start unless I give it some throttle.

Compression test (with a non-rotary tester) said I had even compression on all faces, but only had about 90-95 PSI max. The car has maybe 50 miles on it after the rebuild, so this may be normal.

Below 0 psi the car runs great. No problems at all.

I have not tried coils yet, but I don't understand how these could be the problem exactly at 0 psi (and completely die, not just run rough). Does anyone have any ideas before I buy a new coil pack and/or throw in the towel and ship it to someone?

If you have some good ideas and want to talk, I would love to talk to you over the phone. PM me your phone and I will call.

Thanks so much for everyone's help.

 

Two more items,

Looking at the check sensor screen, it appears that my O2 goes to 0 when the problem happens, and the "FPR" cell lights up. I am not sure if they are a coincidence or not, but it something new.

 

Even more information - If I disconnect the hose from the intercooler (so no boost at all) the car runs completely fine. I can floor it and the car runs like a top.

This really isolates the pressure side of things. What could be causing it so my system doesn't work at all under boost?

 

Judging by replies, everyone else may be as stumped as I am. However, I did run a few more tests I wanted to share to see if anyone knew about them.

1. Fuel pressure is good, and is connected to the right rails. 40 PSI or something when it gets close to 0 PSI. 28 or so at idle.

2. Timing seems to be OK around idle, and advances as RPM goes higher. The white thing on the wheel is hard to see with my timing light (when I can see it it seems to be in the right place), but the thing that sticks out from the cam position wheel is easy to see and is always just after the second cam position sensor. Based on the picture in the manual, this seems to be right.

3. I checked pulse width from the ECM, and it increased when MAP increased. It continued to pulse (around 40%) when the engine was dying around 1 PSI.

4. I disconnected the MAP sensor and tried revving VERY carefully. It ran like crap in vacuum (of course), but when I tried getting MAP above 0 PSI it would still die.

5. I randomly found out that upon startup, if I try and rev the engine in the first few (maybe like 15 seconds), it WILL run under boost under 4000 RPM. Roughly, but it will run. Then it returns to "normal"; if MAP goes above 0 PSI and RPM is below 4000 the engine just goes silent and dies.

Thanks if that jogs any thoughts.

 

I don't seem to have boost past 4500 RPM.

I get a perfect 10 PSI very quickly at around 3,000 RPM, the car pulls strong, and it seems to be going great. However, when I get about 4500 the car falls flat and boost falls quickly (over like 300 RPM on my trace) to zero or almost zero. If I go into the "no boost" situation and then shift below 4500 it takes a moment for the boost to build again, actually longer than if I had just started accelerating at the low RPM to begin with.

Where should I start in the solenoid system? I assume this is a common mistake I have made.