babydeuce

iTrader: (24)

5.3L in a 63 Nova using a truck 5 wire MAF. I have had an intermittent p0102 for the last month. I replaced the MAF with another 5 pin, no fix. I stripped down the harness and found a bad crimp, so I soldered the connections, still nogo. Installed another pigtail, and ohmed out the lines, everything checks out. I 12V and 5V at the connector. Using EFI live, I can see the MAF output drop to nothing when I get on the car, then it comes back up....I am lost on this one, any suggestions?

Jack

babydeuce

iTrader: (24)

Anyone???? I am at whits end on this.

Jack

babydeuce

iTrader: (24)

Come on guys, I have read every post on the site that the search engine can come up with....short of an SD tune, someone has to have something, I cannot see 2 MAF's being bad out of the box.

Jack

DrkPhx

iTrader: (15)

It's really hard to diagnose intermittent problems like that over the internet. Are you using any kind of service manual to follow? I know it's a conversion, but a service manual is always nice to have when dealing with modern EFI. Anyway, here are some basic tips.

-- DTC P0102 will set if the PCM detects a frequency signal lower than the possible range of a MAF sensor that is operating correctly. So it's either mechanical, a poor connection or a short circuit.

* Measure the voltage from the signal circuit of the MAF sensor to a good ground.
-- It should read 5.0v

Inspect for the following conditions:

• A restricted air intake duct or a collapsed air intake duct
• A dirty air filter element or a deteriorating air filter element
• Any objects that block the air inlet screen of the MAF sensor
• Any unmetered air that enters the engine downstream of the MAF sensor
• Verify the MAF is installed correctly, facing in the right direction

* Test for continuity between ground and the ignition 1 voltage circuit of the MAF sensor. Set the multi meter to ohm to measure resistance.
- If the DMM displays low or no resistance, the circuit has good continuity

Hope this helps.

babydeuce

iTrader: (24)

I appreciate the reply! I have already verified the 5V being there, and have checked continuity on all lines to the PCM. The intake track has nothing to collapse and cause a restriction. Filter is clean, and so is the MAF, both for that matter. I can watch the frequency drop off when I get on it, but it does not do it all the time, hence me digging into the harness, and replacing the connector pigtail. The MAF airflow direction is correct, so that is out. I suppose I could have a vacuum leak only under heavy throttle, so I will look into that. I do electronics by trade, so trouble shooting is easy for me, and I do know how difficult intermittent problems can be. I was hoping someone might have seen this same issue before.

Jack

LS1-450

iTrader: (33)

For clarification.....the MAF worked initially & only has had this problem for the last Month? If this is the case, check the wires from the MAF all the way to the PCM. Any other PCM codes, like any "low feed voltage codes"? Even a partially melted 02 sensor pig tail could cause an issue elsewhere. There are several 5V circuits in the PCM that are internally linked. For this reason, a short in a different circuit could show up in a MAF, TPS, MAP....etc.. Not likely in your situation, but am trying to come up w/ something.

RedWS6 00

Something is loose somewhere. That signal is going missing somewhere, if the power to the MAF gets lost then the output will go,but as you have check the continuity it probably not that. I once has MAF troubles on my 3rd gen took me a while to find it. The car would cut out sometimes, it was a hard one to find. I looked under the hood with the engine running, and tapping components to see if vibration would cut the car up, gave up in the end, closed the hood, and then the car shut itself off.
Wasn't battery terminals shorting on the hood. Tried it a few more times, and it was the MAF, every time I knocked the MAF the car would stumble. In the end if was a MAF wire inside the MAF, them really fine wires with the resistors on them, most of the time it connected, but every now and then it didn't.
You say you have replaced the MAF so its probably not going to be that.
How about where the MAF wires goes into the PCM, are all the connectors clean there?
If the output of the MAF signals wire shorts to GND, that could also give simular results to and open circuit.

Hope you find the problem, it must be frustrating.

babydeuce

iTrader: (24)

Thanks for the suggestions guys, I appreciate your input. Just to clarify, the whole story goes like this: Went to a car cruise, car ran awesome, only 300 miles on the conversion. On my way out of town to come home, I stopped for gas, and hit a huge pothole, smacked the passenger side header hard enough to dent one of the tubes pretty good. Filled up on fuel, headed out of town. About 3 miles down the road, car started bucking and popping under any acceleration. First thought was bad gas, but I only got 3 gallons on a 16 gallon tank. SES light came on, pulled a P0102. Limped the car home 55 miles.

Replaced the Maf, and both 02 sensors, still same sympstoms. Tore down the wiring harness found a bad crimp on the signal wire to the pcm. Replaced the connector pigtail, soldered all connections, ran great for about 15 miles, started bucking again. Dumped a bottle of "Heat" in the fuel tank to dry out any water.

I put the car in the air to check the header thinking I may have cracked a tube, everything looks good. Did several scans with efi live, finally caught the MAF dropping out.

PCM connections are inside the car, so no dirt/contamination can occur. Connectors are tight and clean. Only other codes stored are a P0300 which I get at idle only, and cant seem to get rid of.

I find it very odd that this started when I hit the header hard, but I cannot find anything visually that would affect the MAF. All wiring is at least 1 foot away from the exhaust.

All power connections have been checked, grounds are good and solid.

The only thing I can come up with is vacuum leak only at heavy throttle, or a possible chaffed wire where the harness comes into the vehicle.

Frustrating is an understatement, I cant even drive the car to work, as I do not know when she is going to act up!

Jack

RedWS6 00

How about running without a MAF just to see how it drive. Keep it in SD mode. Many guys on here run SD. This will allow you to run to and from work. But doesn't solve your problem of why the MAF comes and goes. You looked at everything I would have suggested.

See5

iTrader: (53)

P0101/P0102 >> Change C2911>> + 100%

DrkPhx

iTrader: (15)

I would physically inspect the wiring to make sure there are no exposed wire.
Maybe the harness got tweaked when you scraped the header and is shorting out when the motor is revved (which torques the motor to one side) causing the intermittent problem. As a failsafe, I would also double check the grounds (especially the one on front lower driver side of the block).

babydeuce

iTrader: (24)

Right now, the VE tables are not right for SD, and I dont have a wideband to tune it properly. Trust me, I have thought about it.

As far as the harness goes, I am with you on this one, I think I may have chaffed a wire that shorts when the engine torques over.

Thanks for all the advise, I will dig into it this weekend.

Jack

babydeuce

iTrader: (24)

Follow up....

I got a wild hair to swap the intake and TB since I had a spare. Took her for a long shake down run today, and had no issues what so ever. I am pretty sure that my issue was a vacuum leak that only appeared when the engine warmed up. Makes sense, it was by passing the maf causing the error.

Thanks for all the suggestions!

Jack

DrkPhx

iTrader: (15)

Glad to hear it's fixed. It's always good post up how the problem was resolved in case someone else has the same problem and finds this thread by searching.