Car Missing Badly After Prolonged Downtime

[5_Liter_Eater]

I tried starting my car today after it had been down without battery power for some weeks. It has been down because I upgraded blower head units from a Novi 1200 to a 1500. This required some different brackets and different air bridge from ECS so I had them send me an LS3 intercooler to throttle body pipe so I could eliminate the MAF housing since I was using the POWRMAF 100mm housing and card style LS3 MAF sensor.

Anyway, I got everything all back together and started it up and it ran like garbage; missing badly and randomly, not being able to maintain a steady RPM and when I gave it throttle it almost dies. The new pipe that that the MAF is in is slightly larger so I tried playing with the MAF tables but it didn't change anything. I switched to VE mode and it got a little better but not much. There was a misfire DTC that I cleared and it has not come back. To me it seems ignition related and I got to thinking that it may need a crank relearn from being without power for so long?

I'm stumped so any unput is appreciated. I know the smart thing to do would be to put the old pipe and MAF housing back in to get it back to how it was but I am not at that point yet.

[EC_Tune]

Spider webs in the combustion chamber... LOL

Not sure what's up if all you did was change the head unit? I'm sure you've done all the obvious so I'm going to ask anyway...

Air leaks
Connectors connected
No tools in the intake manifold
Grounds grounded

Last but not least, Write Entire (Won't help but might make you feel better).

Oh, any codes again?

[5_Liter_Eater]

Air leaks is the concensus ove ron CF.COM although the new setup has less couplers so it should be better if anything. I'll be looking for leaks today in the intake as well as the catch can/PCV setup.

Connectors was the first thing I thought but MAP, TPS, MAF are all connected and there are no DTC's to indicate there are any connectors disconnected.

Haven't checked for tools in the intake

I did change the battery too as the old one had a crack in the top of the case, but both + and - are hooked up and I didn't take any of the chassis grounds off. Something else I failed to mention was I gave the battery wires a bath in baking soda and water as well as the battery tray area. the PCM is right underneath so if any battery acid was on the PCM harness the baking soda should have neutralized it.

I was thinking a write entire too, just for fun.

No codes after I whacked the misfire code.

[kllrvet]

Bad gas from sitting?

[Bluecat]

Connectors connected
No tools in the intake manifold
Grounds grounded

That was good for a morning chuckle.

[Bluecat]

Bill, it really looks like a air leak. It would have to be lean from the size of the airflow numbers and injector pw. And since the maf hz also looks low and the fact that hz to g/sec numbers look reasonable for a card maf (2000hz-6g/sec), it definatly looks like air is skipping the maf. I would have to think your car would eat more than 6 g/sec @ 1200 rpm and 10% tps. I don't know how big your injectors are (I'll assume 60's), but I doubt 1.2ms is enough fuel to make it idle happy.

Now see, if you have a good SD tune running under your maf you could turn the maf off and trouble shoot....

[5_Liter_Eater]

I did try running SD and it ran better but, as you eluded to, my VE is not exactly spot on so it didnb't aid much in the troubleshooting. A little air leak is not enough to make me give up my new cad style MAF. :P

[Bluecat]

So, you have or haven't ran the card style maf before having this problem?

[5_Liter_Eater]

It was working great with the card style MAF in the POWRMAF housing prior to this. I just got the LS3 IC to TB pipe when I got some other parts from ECS to clean up the intake tract.

[Ben Diss]

Have you talked to Doug at ECS? He uses a different brand of software, but he's pretty crafty with this sort of thing.

[5_Liter_Eater]

No. It was fine with the POWRMAF housing and it should be very much the same with the new LS3 pipe. I'm just missing something. I'll figure it out tonight.

[Bluecat]

Any time you change the intake plumbing, especially on those sensors, you can really change the maf calibration. I still think your sucking un-metered air. But in case your not, go back to an old log and see what airflow and pw you were idling at. See what the difference is and scale your maf table by it and see what happens.

[5_Liter_Eater]

Well I played with it last night. I could not see any obvious air leaks so I changed back to the POWRMAF housing and LS2 pipe and edited the tune back to how it was before the car went down for the head unit swap. It ran much better but the miss is still there, it's just less pronounced. Whats worse is my brand new head unit is leaking like a seive! So I doubt I'll have time to troubleshoot the miss anytime soon as the unit may have to go back to Paxton AGAIN, or maybe in the dumpster.

[DSteck]

Did you check your plugs yet? You never know... it could be something simple.

FYI, the A&A Vortech kits are awesome.

[5_Liter_Eater]

Could be. I may do some more poking around before I rip this head unit off.

Yea, I really like Andy's new IC design. Still, Vortech and Paxton are almost the same company so I'd be leery to go with them.

[EC_Tune]

Bill, stop screwing around and get an F1R... Just kidding, you need two of em!

[5_Liter_Eater]

Apparently the brain trusts at Paxton simply overfilled my unit. Took some oil out and it doesn't appear to be leaking anymore. But, the car still misses badly. It comes and goes. On the way back from a test run it was even bucking; when cruising down the roar @ ~2500 RPM's it would even buck hard. I tried pulling plug wires and injector harnesses on individual cylinders and it didn't even make a difference in the way the engine ran.

Starting to think the MAF is bad. The MAF chart looks OK then gets very erratic then OK again. Tomorrow I'll try switching to SD. Attached is a log file of the bucking and here's a video:

[1.8t]

I am glad I am not the only one who names my logs by the frustration they cause me haha.

[WS6FirebirdTA00]

bad MAF is a good candidate, how do the plugs look?

[5_Liter_Eater]

I only looked at the passenget bank and they all looked fine. I'll check the drivers side tonight and switch to SD and report back.