Im having a weird issue with my 89 Iroc. Its having a weird bog when im getting up in the RPM range. Its sparatic tho. It doesnt happen all the time but in my logs im noticing my RPMs steadily increasing but when the bog is happening im noticing my MAF will start decreasing. Shouldnt my MAF output steadily rise with RPM since the motor is constantly sucking in more air. I think im battling a bad maf but if someone out there is willing to look at my logs and give me an answer id be glad to send them. Thanks for any help

 

Could be the ducts on the intake are collapsing and restricting air flow.
Something to check into.

 

I don't think it's the duct. It starts to happen when the Maf misteriously starts reading lower voltage causing the pw to lower and the motor leans out. I'm really close to either going speed density or selling my TPI and auto prom and adjusta jetting my Holley and going carb. I would like to keep FI but it's just getting frustrating and the only concern about doing carb is I used to always have fuel slosh problems when I would stop and turn.

 

Can you post a log file?

 

Not sure how to post a log file on here. I have one i took this evening that would be perfect to examine. PM me ur email and i can shoot it to you.

 

Use pastebin.

 

Ok couldnt figure out how to use Pastebin since its only txt but i zipped the log and i figured out how to post that. The worst bog happens when the car hits 147 Degrees temperature. I really believe its the MAF since it climbs evenly with RPM untill MAF reaches around 200 then the bog occurs and even if RPMS increase the MAF will stay around 200 if not lower. Any insite from others would be usefull before i go spend $130 on another MAF.

 

Well I would try to help by looking at your log but I have no power, just my phone but if I get power back ill take a look.

 

Well its not the MAF, bought a reman from O'Reillys and it didnt make a difference. Anybody willing to look at my logs and help me out PLEASE

 

In this last log when does the bog happen?

 

In the last one they are all around 4800. I just realized I have a code 42 but the ses light isn't coming on so I'm going to try and diagnose that.

 

did you check, the fuel pressure. maybe clog fuel filter or a fuel pump going bad. might get good pressure at idle but as rpm go up fuel press might not keep up.

 

I thought about that too and it will be my next thing I check, it's just hard to get a fuel pressure reading while blasting down the highway at 5000 rpms.

 

If you have a code 42 then you need to start there, its a EST fault, check make sure your chip is seated properly and that the est wire is pluged in first.

 

Well the code 42 came from when I set my timing and never reset the ECM. I have the layout of code 42 diagnosis so I'm going to go thru that if that all checks out I'm going to look into fuel. The pressure readings all look good at idle and my check gauge should have enough hose so I can tape it to the windshield.

 

Well the ICM seems ok, has the correct OHMS on the D4 white wire and no code 42 anymore. Also Fuel pressure seems fine throughout RPM range. The Bog seems to get worse as u go thru the gears. 1st is barely if not noticable at all, 2nd is worse, and 3rd it gets bad enough to hold the car around 4500 for a few seconds before it will accel past that. I think it might be the AIR system. Its been removed by previous owner. Im noticing that its trying to Divert air when im going WOT. Im going to try and figure out how to disable AIR and see if it makes a difference.

 

Well it's not fuel pressure. I'm fed up, im bout to just sell my auto prom and TPI stuff and put my holley on. Unless someone gives me a magical answer.

 

Well i think im on to something. Im noticing when the bog is occuring im noticing drops in my O2, making me think its ignition since if it isnt getting spark then the O2 would be picking up the unburnt charge and making the drops in O2. I might try a new Distributor and rotor and cap since the rest of the ignition is new.

 

I've looked at both of the logs you posted and dont see a dead give away for your problem, the only thing I noticed was in the second log the your first pull through 1,2, and 3 gear, in 3 gear at about 85mph the tps goes flat then jumps right back up, now I'm not sure if you just let off the throttle but if you didn't then you might want to check out your tps sensor.

 

I'm pretty sure I let off cus on all my other logs the tps stays the same.

 

See if you can post your bin for us to take a look at.

 

Ok so i made some progress today. The new dizzy definatly made a big difference. It pulls much harder and idles much smoother than before. But im still having a bog starting around 3800-4800. I notice the bog is much less if not present at all if i roll in the throttle easy, which i was having to do cuz of the wet roads. But if u punch it hard tho its pretty noticiable thru 3800-4800 then it picks up great and goes till i shift. My oxygen sensor is showing 920-930 milivolts so i dont think im running lean, the only thing i can think of is i might need some more timing. Im only getting 34-35 degrees at those rpm ranges so i might add a degree or two and see if it helps when i can get some dry pavement to really punch it on. Also here is my latest log and my Bin.

 

Is this the bin you are using? I dont know much about 6E bins but this bin looks like a stick bin, does your torque converter even lock up? Where did you get this bin from?

 

Yes it is the one im using. Its a APYP bin from tunerpro site with just a few things tweaked. What looks wrong with it?

 

Would you be willing to give this bin a shot, not saying to keep it but just to test out, see if the bog goes away.

TRY THIS.zip

 

Ill give it a try, it looks like the bin im using now except a the spark table is a little different. Im wiling to try anything at this point. But again, what looks so wrong with the bin im using?

 

All the TCC and ICA settings look like a stick shift bin to me.

 

APYP: not a good BIN to start with regarding your set up. It is for an aluminum headed L98 with a manual 6-speed trans.

You would be better off with ARAP, then copy in stock iron headed SA tables, flip the fan logic flag (so it is off on a cold engine, and on on a hot engine), and changing the cranking PW vs DRP table for faster starts.

With the cam will still need to tweak the SA tables some. But they will be better then APYP.

As for the bogging, make sure that the TPS voltage isn't going over 4.7 volts at WOT. If it does the ECM will drop out of PE mode. Can verify this by checking the commanded AFR at that time.

RBob.

 

Well i decided to try the bin the car came with and it made some difference. The bog is not nearly as bad but it did do it once around 4500 as always. Here is the bin and my 2 logs i did today. Any advice would be helpful.

Also now when i drop it in third and floor it it will pull till around 4000 then the rpms will drop a few hundred as if the torque converter is locking and it keeps climbing. Is this normal?

 

What is rev limiter set to?