Car Missing Badly After Prolonged Downtime

[EC_Tune]

If the head unit was overfilled what's to say that some of that oil didn't go into your intake & contaminate the MAF. Try some electro-contact cleaner on it.

[5_Liter_Eater]

Tried that already but I'll give it another go. Changing out the plugs and wires tonight. I pulled apart a wire when I was checking the plugs, which all looked OK. Black around the bottom of the threaded part, the electrodes looked good and the unsulators were all nice chaulky white/tan. Gap had opened up a scosh to ~just under .040". They come gapped @ .035".

[vortech]

I think the newer MAF's are real sensitive to anything getting on the wires. If the blower was overfilled it could of hurt it. I would just try swaping out ot another sensor and see if it helps.

and just like EC said-just put an F!R on it!

[5_Liter_Eater]

Put new plugs (TR6's gapped @ .030") and wires in and it runs OK. It still misses, stutters @ idle. It will hold 750 like a rock for ~10-15 secones and then hiccup down to 650 or so for a second, then come back up for 10-15.

The hard drive on my tuning laptop died so I'm without HPT for a few days while I rebuild it. I'm not sure if it's an injector or a coil or maybe just adaptive idle advance, it seems much smoother when moving.

[WS6FirebirdTA00]

Might have been brought up somewhere in here (too lazy to look ) but what about the gas?

OK, not so lazy, I see post 4 has it but no comment on it...

[5_Liter_Eater]

It's run through a full tank of new gas now. 93 octane. Got my laptop rebuilt. Enabled STFTs and they look very similar bank to bank so to me that is a dece nt indicator that I don't have a bad coil or injector. I wish the cylinder balance test worked on the E40's. Any key things I should log? Individual cylinder misfires?

[5_Liter_Eater]

So it's running a little better now but nowhere near where I'd be happy with it. The stumbling at idle is much better. When cruising you can feel it stutter. Like it's still slightly missing, like a weak spark or something. So I'm still thinking coil(s) or injector(s) but really the only difference is the head unit which flows 200 CFM more than the previous one. Could it be that the Bosch bypass/blowoff valve is not smoothly dumping the excess air? Unlike a turbo application this valve is open all the time unless WOT. If it's not dumping enough air or fluttering then my wirflow would be erratic.

[EC_Tune]

How far ahead of the MAF is the blowoff?

[5_Liter_Eater]

The BOV is attached to the opposite side of the intercooler. So air comes in from the right and exits at the top, the BOV is on the left. So the air goes through the IC, then through ~18" of intake pipe before it hits the MAF.

Any tips on what I should be logging to help troubleshoot this? I'm about ready to take it to the dealer to have them hook it up to the TEC-II. Is there a way to test the coils? I'm about to take the injectors out to have them flowed too.

[MattD]

Have you tried another MAF yet?

[WS6FirebirdTA00]

From his earlier posts, he said that it acted similar in SD.

[EC_Tune]

Put your misfire monitors back to stock & use the misfire config to see which cylinder(s) are giving the biggest issues. Should show up nicely with your cam.

[WarWagon]

Look at your 2nd log for the ms time on the injectors and then the O2 reading. Looks like the computer is cutting fuel way down then the RPMs drop and a lean reading shows up. (So computer commands lean, possible lean misfire, and then lean exhaust reading.) Your wide band O2 even shows this in the video.

Really acts like it wants more fuel. But the computer isn't putting out.

I'd say that the coils and injectors are fine as the computer is cutting the ms down on the injector pulses. A old fashioned spark line tracer to see the firing voltages may help show you a lean condition or not. (Your smaller gap allows a leaner mixture to fire.) This does not rule out a problem with the MAP sensor or sensor wiring/connections. You may want to revisit the (solved) cracked battery. Did it leak? Did the baking soda solution get into the PCM or electrical plugs? Both are corrosive. For grins check for grounds in that area.

Could the oil leak also be a vacuum leak in the S/C?

Otherwise the different airflow of the 'larger' blower may be wigging the tune out by moving more air at these lower rpm's than the smaller unit did.

Did it adjust the timing and the ETC position as much with the other blower? It looks like the computer is adjusting everything it can to obtain a idle speed and starting to oscillate. Maybe going higher on the idle? I'd try the VCM controls with raising idle speed. Just so you can see a wider oscillation and maybe catch what makes it start.

[5_Liter_Eater]

Those are some good points, especially about the PW's. PW's being cut down would have to be a result of percieved loss of airflow. I think it's time to swap back to the old LS2 MAF like Matt said. I'll try that this weekend. It's a relatively easy (and free) change that will rule out the MAF as the source of the problem.

PCM corrosion is a possibility. I gave the battery tray and surrounding area a nice baking soda bath. I thought the baking soda neutralized the acid.

The problem is exhibited off idle too. Cruising down the highway @ 1500 - 2500 RPM and you can feel it stutter, like the brakes are being tapped. This takes the closed loop idle functions out of the equation. Here is a log with the misfire history logged as well as a screenshot of the peaks of the misfires. I don't know ifthe numbers are indicative of a problem but #6 has more than double any other cylinder.

Thanks for the replies. I have to admit I haven't been on top of trying to resolve this problem.

[WarWagon]

Is it just me or is your fan % going crazy? I assume you have your wide band hooked up to the AC pressure? If so I would flat line the AC fan table just in case the fan is throwing an electrical load that is messing up the computer. Bad ground, too much current to speed it up, whatever. Eliminate that variable.

[5_Liter_Eater]

Spot on about the WB through the AC. Good idea about flatlining the fan table.

[5_Liter_Eater]

Today I swapped back to the old LS2 MAF. Problem solved immediately. Idle is solid again, cruising is back to smooth and WOT is back to Holy $h1t! Granted I'm off my MAF table by ~5300 RPM and having to use PE from then until redline but its great to have a nicely running car again. So something is whacky with that LS3 MAF but it didn't act like that when I initially put it in. Eventually I'll get another one and try it again but for now I'm just going to enjoy the car for a little while.

Thanks for everyone's input!

[EC_Tune]

Glad you found the problem Bill! MAF's are cheap though.

[Ben Diss]

Excellent.

[LazMan]

MAFs are cheaper than engines, yes. That was a tough nut to crack!