ARGGHH!!MAP & MAF, O2 sensors AND I'VE HAD IT!
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Registered User
Joined: Oct 2007
Posts: 61
From: Louisiana
ARGGHH!!MAP & MAF, O2 sensors AND I'VE HAD IT!
Hi all, I'm close to pulling out my hair and taking a chainsaw to the car.....
First, I should say, we have fixed some assorted issues recently, new TB 52mm (had a vac leak there, linkage worn out), a wiring repair going to the o2 sensor (the engine bay side of this), and REALLY was hoping this would solve most of the trouble. Nope, of course not.....Sorry, this will be long.....
The car runs rich, rich rich, no raw gas pouring out of the tailpipes, but not good either. I have a couple of logs from Datamaster from last night, and I believe the right o2 needs to be replaced, it never really functions out of the 300 to 450mv 'ish range in closed loop. We get a DTC 33, can't get rid of it so far. There numbers from Datamaster are: BAR 102.6, MAP 73.5kpa at 875 RPM, Fuel trim 16. AFGS 14.07, TPS volts .69, IAC 81. The PCS is making fuel corrections all over the place.... Once into closed loop for a couple of minutes, I gave it a little gas, went into fuel trim 18, 1750 RPM....Right bank LT 119, short term 116, Left bank LT 122, short term 116. At this time in the log, BPW 2.11 left, 2.03 right. Inj DC 3.1 left, 3.0 right. TPS volts rose to .80. Spark advance 41.0, no spark retard, TPS% 3.1. MAP Kpa 51.3. If anyone can tell me how I can get this uploaded somewhere so it can be looked at. I can never drive the car hooked up to Datamaster cause the laptop battery will not charge. I am concerned about the high MAP, and the code, and why is it so rich. Maybe the AFGs are off as well? The MAF is descreened and was ported, from my understanding by previous owner. Is this causing some/ all of the trouble? As far as MAP, is the cam (Comp Cam 290/307 .510 intake, .540 exhaust, 112 lobe sep) causing this to be a high pressure/low vaccum situation? The PCM seems (correct me if I am wrong) to be thinking the engine is under a load at idle and a little above, and is dumping fuel at it. Again, correct me if I am wrong, cause chasing this one is making me nuts!!!! Will be checking the wiring for MAP today, MAF wiring is ok. BTW, The car has a new 255 Racetronix setup, new 42 lb lucas injectors, new TB, MSD 6AL, new MSD wires, and a new tune. I can't drive my car, and my pocketbook is getting lighter.......
First, I should say, we have fixed some assorted issues recently, new TB 52mm (had a vac leak there, linkage worn out), a wiring repair going to the o2 sensor (the engine bay side of this), and REALLY was hoping this would solve most of the trouble. Nope, of course not.....Sorry, this will be long.....
The car runs rich, rich rich, no raw gas pouring out of the tailpipes, but not good either. I have a couple of logs from Datamaster from last night, and I believe the right o2 needs to be replaced, it never really functions out of the 300 to 450mv 'ish range in closed loop. We get a DTC 33, can't get rid of it so far. There numbers from Datamaster are: BAR 102.6, MAP 73.5kpa at 875 RPM, Fuel trim 16. AFGS 14.07, TPS volts .69, IAC 81. The PCS is making fuel corrections all over the place.... Once into closed loop for a couple of minutes, I gave it a little gas, went into fuel trim 18, 1750 RPM....Right bank LT 119, short term 116, Left bank LT 122, short term 116. At this time in the log, BPW 2.11 left, 2.03 right. Inj DC 3.1 left, 3.0 right. TPS volts rose to .80. Spark advance 41.0, no spark retard, TPS% 3.1. MAP Kpa 51.3. If anyone can tell me how I can get this uploaded somewhere so it can be looked at. I can never drive the car hooked up to Datamaster cause the laptop battery will not charge. I am concerned about the high MAP, and the code, and why is it so rich. Maybe the AFGs are off as well? The MAF is descreened and was ported, from my understanding by previous owner. Is this causing some/ all of the trouble? As far as MAP, is the cam (Comp Cam 290/307 .510 intake, .540 exhaust, 112 lobe sep) causing this to be a high pressure/low vaccum situation? The PCM seems (correct me if I am wrong) to be thinking the engine is under a load at idle and a little above, and is dumping fuel at it. Again, correct me if I am wrong, cause chasing this one is making me nuts!!!! Will be checking the wiring for MAP today, MAF wiring is ok. BTW, The car has a new 255 Racetronix setup, new 42 lb lucas injectors, new TB, MSD 6AL, new MSD wires, and a new tune. I can't drive my car, and my pocketbook is getting lighter.......
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Joined: Nov 1998
Posts: 71,094
From: Hell was full so they sent me to NJ
You're getting DTC 33 for the high MAP reading because of the 73kPa reading at idle. Anything over 68kPa and you get the code set. In effect, the engine only has about 8.5"Hg vacuum at idle. I have no idea what a "290/307 Comp" cam is. What is the duration at 0.050" and the LSA?
The PCM uses MAP as a measure of engine load. You've got to figure out why the engine has no vacuum. Maybe the cam it big enough to cause that, but without the specs, its hard to tell.
I told you in your thread on LT1/LT4 Engine Tech how to upload the data log.
If your laptop battery won't charge, simply buy a small 12V DC-> 120V AC inverter, plug it into the cig lighter and plug the laptop power supply into the inverter. The power supply will tell you how many watts you need for the inverter. Blipping the throttle at idle is virtually useless with regard to providing data.
The PCM uses MAP as a measure of engine load. You've got to figure out why the engine has no vacuum. Maybe the cam it big enough to cause that, but without the specs, its hard to tell.
I told you in your thread on LT1/LT4 Engine Tech how to upload the data log.
If your laptop battery won't charge, simply buy a small 12V DC-> 120V AC inverter, plug it into the cig lighter and plug the laptop power supply into the inverter. The power supply will tell you how many watts you need for the inverter. Blipping the throttle at idle is virtually useless with regard to providing data.
Thread Starter
Registered User
Joined: Oct 2007
Posts: 61
From: Louisiana
Sorry for the lack of info. Here is everything on the cam card. The Part number 07-306-8. The Grind # is Lt1 290hr-12. The gross valve lift is .510 intake .540 exhaust. Duration at .006 tappet lift 290 intake 307 exhaust. Valve timing open at .06 Int
pen 37 BTDC close 73 ABOC Exh: open 90BBDC close 37ATDC. These specs are for Cam Installed at 108 Intake Center Line. Duration at .050 Int: 230 Exh: 245 Lobe lift int: .3400 Exh: .3610 Lobe separation 112.0. I realize you may not need all this but just incase I posted it. Also I installed a vaccum canister on the car to help with the low vaccum at idle. I will go back to my last post and read how to upload the data logs. Do you think that I need a MAF that has not been de screened or ported? Could this have anything to do with my problem. Injuneer Thank You Once Again.
pen 37 BTDC close 73 ABOC Exh: open 90BBDC close 37ATDC. These specs are for Cam Installed at 108 Intake Center Line. Duration at .050 Int: 230 Exh: 245 Lobe lift int: .3400 Exh: .3610 Lobe separation 112.0. I realize you may not need all this but just incase I posted it. Also I installed a vaccum canister on the car to help with the low vaccum at idle. I will go back to my last post and read how to upload the data logs. Do you think that I need a MAF that has not been de screened or ported? Could this have anything to do with my problem. Injuneer Thank You Once Again.
Registered User
Joined: Dec 2005
Posts: 372
Has your PCM been properly tuned for the inj., TB, Cam and MAF? If not or if the program was tuned with a mail order tune often times they are off to the rich side and need anywhere from a little to a lot of tweeking done to them. A .uni file would help diagnose the issue from datamaster however.
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