Relocating MAF, code 66, long story, barely running? Help?

[sirhk100]

Hey guys, finishing up a full offroad build but posting this in here figuring it's a stock related part...

Here's the thing. Cause of some modifications I've made to the engine compartment and shock mounting setup, I was left with only 1 option of mounting the air filter and that was on the drivers side between the radiator and the coolant overflow/window fluid tank. Now I was a bit skeptical about doing this worried that extending the harness may mess up the resistance in the harness cause I know some older vehicles engineered the harnesses this way but I went for it anyways. I added about a total of 12-15" of harness length to the MAF sensor. I soldered the harness, no goofy butt connectors or anything like that.

Now I finally got the truck ready for it's test drive. It's about 95-99 degrees here in Vegas today. I first took it for a spin around the neighborhood. I've got an ENTIRE new front suspension system with a lot of custom work done. I was checkin for handling, brakes, clunks and noises, etc... I did NOTHING to the engine though other then unplugging and plugging back in a few harnesses and the MAF harness extension. It ran fine. So pulled it back in the drive, made a few suspension tweaks, double checked a few things and went for a road test to run an errand actually. Left the house, Did about 10 miles of city street driving. Stop lights, a little traffic down near the strip, etc... Everything great!!!

Ran into a store for about 30 minutes, came back out, fires up great. Take the long way home and hop on the freeway. Cruising along at about 70mph for about 10 or so miles. It's well warmed up at this point, like I said, we pushed 100 degrees today. All of a sudden I'm loosing power... It doesn't just die instantly but I can tell it's sputtering and going down. I get off to the median and make a choice to coast it to the next offramp with the momentum I have. BTW, it's a 5 speed manual trans. Get well off the freeway and figure it's gotta be wiring related cause I didn't do anything else. I check a couple plugs, nothing... Well, actually at this point, what it's doing is it'll start and idle but any throttle and it just about stalls, pops, sputters, backfires thru the intake, etc... After a bunch of wiggling it fires up though, I toss on my seat belt and pin it heading for city streets homes. It basically ends up to the point where it'll run for about 45-60 seconds, then falls on it's face. I coast to a stop, turn it off, wiggle wires, back in and go for another round. Takes me about 6-7 rounds of this to get to my driveway.

In my driveway I look at the plugs I'd messed with. I find one with only 2 wires on it and they're both bare for about 3/8" right as they go into the plug!!! BINGO!!!! I can deal with this... Insulate them and figure game on! It fires right up in the drive so I decided to run to the store with it.

I make it about 1/2 mile and it's doing it again. CRAP!!! I jump thru the routine of wiggling wires still thinking it's gotta be related to that. I get back home.

I plug in a fairly decent OBD1 scanner I have. For some reason I've never been able to connect to do a engine on scan but I've been able to do key on engine off scans.

The only code I pull is a 66. MAF voltage too low.

CRAP!!!! Is this due to my extended harness?

My hesitation with assuming that is why was I able to drive it for probably 20 minutes on the city streets problem free, then another 10-15 minutes on the highway problem free before it gave up? I'd have thought if it was related to my harness it would've been doing it from the get go, not 30-45 minutes into a test drive?


Thoughts? The expo has been sitting for about the last 6 weeks during my build. I have started it for a couple minutes probably about 3 times during that duration but didn't drive it at all, just let it idle up to temp and that's about it.


I've got another expo to rob parts from... I actually was going to pull that plug with the bare wire and splice it in as a replacement but the one on my other expo isn't using the same pins. My problem expo has only 2 of the 8 possible pins in use where my other is using like 6 of them. The other one is an auto trans though so I'm guessing that's the difference.




So, Code 66, MAF voltage below minimum, is it cause I extended my harness? If so, why did it take 30-45 minutes to start acting up? If it was a warm up issue I know darn well it was at full operating temps WELL before then.

 

[sirhk100]

BTW, every other vehicle I've owned, if I unplug the MAF harness it won't run. When I unplug this one I notice a slight increase in RPM and it still runs.

Is that normal?

 

[jd4242]

I extended mine and didn't have any issues. Did you reset the computer after fixing the bare wires? Maybe it shorted out the maf, may try new electronics from a spare.yes it should run with it unplugged.have you test driven it with it unplugged? How long did it sit? May be a combination of bad maf and bad gas

 

[sirhk100]

Did not reset the computer... To do that, pull terminals, touch together, put them back on the battery?

The bare wires were on a plug not related to the MAF. Not sure what they were for, there's a couple of round type plugs attached the the inner wheel well on the driver side. It was one of those.

Have not tried driving it with it unplugged. Just did a couple common things last night and then called it a day. I was out in the garage for 10 hours or so total yesterday and when it pulled this crap I was just mentally over it. LOL

Sat for probably 6 weeks at the most. Ran GREAT for the first 45 minutes of the drive yesterday.

Now that I think about it though, the MAF sat on my bench for the last 6 weeks and if it looks anything like the expo itself did from all the grind dust it's probably pretty dirty. I'll pull it apart and clean it and start there.

Would a MAF cause the symptoms I'm having, rough to almost won't idle, hit the throttle and pops and sputters and back fires thru the intake. When it goes from running to not running it sounds almost like it's missing on a couple cylinders and just doesn't have any power.

 

[jd4242]

Did not reset the computer... To do that, pull terminals, touch together, put them back on the battery?

The bare wires were on a plug not related to the MAF. Not sure what they were for, there's a couple of round type plugs attached the the inner wheel well on the driver side. It was one of those.

Have not tried driving it with it unplugged. Just did a couple common things last night and then called it a day. I was out in the garage for 10 hours or so total yesterday and when it pulled this crap I was just mentally over it. LOL

Sat for probably 6 weeks at the most. Ran GREAT for the first 45 minutes of the drive yesterday.

Now that I think about it though, the MAF sat on my bench for the last 6 weeks and if it looks anything like the expo itself did from all the grind dust it's probably pretty dirty. I'll pull it apart and clean it and start there.

Would a MAF cause the symptoms I'm having, rough to almost won't idle, hit the throttle and pops and sputters and back fires thru the intake. When it goes from running to not running it sounds almost like it's missing on a couple cylinders and just doesn't have any power.

Yea just unplug the battery for awile.definitely clean the maf.hmmm it could act that way but seems like there may be more to it, why I was thinking bad gas but it didn't sit to long.may wanna throw a new fuel filter in if you haven't in awile, with fresh gas.shot in the dark tho

 

[sirhk100]

I've only owned it for about 3 months so not sure on the fuel filter but wouldn't hurt either way even if it doesn't fix this issue.

It's odd though, yesterday I could start it, make a mad break for it running it for 45 seconds or so to get up to speed before it would start sputtering. Then pop it in Neutral and coast it out to get the distance and repeat. Made for a long drive home! LOL

That sequence though is partially why I'm not sold on wiring or MAF. I'd think it would either run or wouldn't run. The fuel filter type issue does kinda make sense though. Stuff settles let's me run for a bit before it gets plugged. I just figured with the code 66, and the fact I had messed with a few wires, it just seemed like it would make the most sense to target those areas for the problem.

The reason I had to relocate my MAF... No room where it was, the battery is still in the stock location so I couldn't stuff it there.

 

[jd4242]

I've only owned it for about 3 months so not sure on the fuel filter but wouldn't hurt either way even if it doesn't fix this issue.

It's odd though, yesterday I could start it, make a mad break for it running it for 45 seconds or so to get up to speed before it would start sputtering. Then pop it in Neutral and coast it out to get the distance and repeat. Made for a long drive home! LOL

That sequence though is partially why I'm not sold on wiring or MAF. I'd think it would either run or wouldn't run. The fuel filter type issue does kinda make sense though. Stuff settles let's me run for a bit before it gets plugged. I just figured with the code 66, and the fact I had messed with a few wires, it just seemed like it would make the most sense to target those areas for the problem.

The reason I had to relocate my MAF... No room where it was, the battery is still in the stock location so I couldn't stuff it there.

Lol I was just looking at you pics.sweet work man.are those glassworks fenders? If so they screwed me hard, but that's a long story.yea filter won't hurt and could have sucked some crap in it and with the maf dirty could really affect the afr.then when you get off the gas it builds pressure again for a bit but still running like crap because of maf.like I said shot in dark but both very cheap and easy to fix so I would start there.of course check all vac hoses for cracks or anything also, like to exspand when hot.

 

[sirhk100]

They're McNeil's fenders and I'm happy with how they fit. I'm used to glass fitting really bad, this isn't my first offroad truck with fiberglass by any means.

This whole not running thing is a bit of a bummer! I'm pretty darn anxious to get it up and running not to mention have A/C since my daily driver right now is my toyota pickup which is flat black with no interior other then 2 seats and a dash basically with no a/c and we're supposed to hit 99 here today so it'll be nice and cozy in there on my lunch break and trip home.

Will see what I can find on it tonight... Thanks for the help.

 

[2000StreetRod]

wire extension length not the problem

I extended my 2000 MAF sensor wires a similar amount with no issues. Since you're getting code 66 you should make sure your MAF sensor wires are making good electrical connection and not shorted to each other or chassis ground. Does code 66 show up right away or only after the vehicle has been driven for 20 minutes? The PCM may be ignoring the MAF sensor output since it's voltage is outside of established limits and relying mostly on the TPS to determine engine loading. That would explain why the engine runs about the same with the MAF sensor disconnected. Also, with no functional MAF sensor the air/fuel ratio could be way off. Running that way for an extended period of time could result in the symptoms you're experiencing. I suggest disconnecting the MAF sensor electrical connector and the PCM connector and then measuring the resistance end to end of the BRN/WHT wire and the DK BLU/LT GRN wire. According to my Haynes Repair Manual your 1991 should have three wires connected to the MAF sensor. There should also be a BLK/WHT wire.

 

[Roadrunner777]

You may find this usefull:

http://easyautodiagnostics.com/ford_maf/maf_sensor_ford_1.php

 

[sirhk100]

Okay, I'm convinced the MAF is working fine. Passed every test I threw at it including the link directly above. Thanks for that. It passed it when it ran good and even though it took a friggen miracle to get it to run rough I finally managed to coax it into it's pissed off mode and the voltage on the maf was still stable and still within spec.

I've got a POS crappy harbor freight pressure gauge that I put on the fuel line though while it ran rough. At one point I saw it down at like 10psi but when it ran good it was only reading 30 psi. Not sure i really trust it at all though. But it is something that had me curious. There was times when it read 20 while running rough too, not the most reliable tool in the box, that's for sure but it's something I'm keeping in mind.

I wish I could figure out how to make it stumble on command that's for sure! Would make trouble shooting it a heck of a lot easier at least!

 

[jd4242]

Fuel pump....once it gets hot it starts going bad on and off.like I was saying I would start with filter but sounds like the pump is going bad or the relay.

 

[jd4242]

Also test the fpr.put the gauge on and pull the vac line off the fpr and see it pressure jumps wile running

 

[sirhk100]

My next search was going to be what the fuel pressure should be and tomorrow I'm going to try to get my hands on a quality pressure gauge. Talk about crappy timing!!! I know 100% non of my custom build had anything to do with the pump! LOL And let me guess, it's inside the tank right? Joy joy... Will be doing the filter for sure if I'm doing the pump.

 

[sirhk100]

by the way, when running good I pull the maf plug and it seems like it may change the rpm a tiny bit. When running rough sometimes it doesn't seem like it makes a difference, sometimes it stalls when I pull it. Kinda strange that it's not very noticeable of a difference though typically plugged in vs. not. I did at one point have a check engine light on while driving with it unplugged and then put it back on and the cel went off...

 

[jd4242]

My next search was going to be what the fuel pressure should be and tomorrow I'm going to try to get my hands on a quality pressure gauge. Talk about crappy timing!!! I know 100% non of my custom build had anything to do with the pump! LOL And let me guess, it's inside the tank right? Joy joy... Will be doing the filter for sure if I'm doing the pump.

Hey the go bad but hope its not that.but yea pump is in the tank and filter is in the frame under the drivers seat.could be the relay also, thats in the bay where you could have been messing with all those wires.

I can't remember what fuel psi should be for stock but think around 32ish with vac line on and around 38-42 off..don't quote me tho.

 

[jd4242]

by the way, when running good I pull the maf plug and it seems like it may change the rpm a tiny bit. When running rough sometimes it doesn't seem like it makes a difference, sometimes it stalls when I pull it. Kinda strange that it's not very noticeable of a difference though typically plugged in vs. not. I did at one point have a check engine light on while driving with it unplugged and then put it back on and the cel went off...

If its working properly then there shouldn't be a ""huge"" difference.just mpg and power will suffer but it will run off stored settings (closed or open loop, can't remember ....to late at night) did you clean it atleast?

 

[sirhk100]

well, I'll be doing some research tomorrow for my next list of things to test and go from there... I've got a parts vehicle that I plan to donate for scrap to a charity and was going to raid it of as many spares as possible. I guess that's the one nice thing... I can toss parts at the problem by stealing them off the dead white expo in my driveway before it gets hauled away as a tax write off. LOL Past my bedtime though, will continue my research tomorrow... Good times! I just want this thing running so I can use the A/C before the heat really kicks in around here this summer!

 

[sirhk100]

If its working properly then there shouldn't be a ""huge"" difference.just mpg and power will suffer but it will run off stored settings (closed or open loop, can't remember ....to late at night) did you clean it atleast?

Yes, I pulled it out and sprayed it down with some MAF cleaner I had in my chemicals cabinet! I bought the stuff years ago, don't even remember why honestly, finally got to use it at least. LOL