Liquid_02

Alrighty... When I start up my car, it runs fine without the MAF connected, but when i connect it, the car just stalls out.

I have tried 2 MAF sensors, one I know worked when I pulled it out of a car.

I have a C&L MAF calibrated for 24# injectors, mine are only 19# but it should still run, never the less.

My car is an 87 GT... but everything out of a 92 has been put in it (computer, wiring, dash, engine, tranny, airbags, seatbelts... blah blah blah), so let's pretend it's a 92.

Does anybody have any idea what could cause this? Maybe have experienced it? My dad is a journeyman mechanic of 30 years and he couldn't even figure it out, and it's really frusterating me, I want to get my car to the body shop to get the body put together so i can drive it before winter, and I need it safetied so all has to be working properly.

Possibly something I didn't connect in the swap from an 87 to a 92? Though i've been looking and can't seem to find anything...

vristang

First, the fact that the car runs better with the MAF disconnected does not indicate that the MAF is bad. When the O2's or MAF are unhooked, or the signals are extremely out of range, the computer switches in to Open Loop. Open Loop is basically like running off preset tables and sensor inputs are ignored.

With that said...
You HAVE to resolve the parts mismatch with the C&L befor you can do other trouble shooting. Always fix the known issue before looking for other culprits.
With the C&L you need to have the correct sample tube AND the right MAS (the black sensor on top of the MAF tube).
You should have an F1ZF MAS if it is a Ford original.
The sample tube should not have any color coding and measure .5650" This would be correct for a A9* computer running 19lb injectors.
You can contact C&L for the correct sample tube if you have the wrong one.
I think they run about $25.
I have some more C&L info on my website... http://www.freewebs.com/vristang/clsampletubes.htm

Also, you should start any trouble shooting on these cars by pulling the diagnostic codes from the computer. They will help a great deal.

From your description you could also have a problem with the O2 sensors, but at this point that is pure speculation on my part.

Summary -
Make sure your MAF is cal'd for the injectors you have. There is no hope of the car ever running properly if the MAF and injectors are mismatched.
Pull the codes and make sure you aren't getting any codes. This is a good way to verify that the MAF conversion was done correctly.

If you are interested in learning the real deal on how the EEC-IV computers work then check out the book "How to Understand, Service and Modify Ford Fuel Injection & Electronic Engine Control" written by Charles O. Probst of SAE. You will want the 1988-93 version.
This book will define all the terminology and explain the various modes the computer will run in.

Let us know how you do and good luck,
jason

Liquid_02

Thanks for the great reply

I would have scanned it, but one of our scanners has been sent out for repair, our good one (Mac one). So we have one at my dads shop which I can't take home to scan it because they need it there. That is my only reason for not scanning it.

O2's I bet could be a problem, that was actually my first guess personally. When I bought the car the douche put two nuts in the exhaust with the wrong thread for the O2's and bastardized the threads. I got new exhaust with the 87 and put the proper bungs in it and couldn't get the O2's in because of the bad threads. I got one in, but the other wouldn't even start, so I just kinda jammed the threads so it'd hold it in so i could try it with the O2's but to no avail. From the accident, one of the connectors for the O2 is also broken, I'll check that to make sure it's still passing current tomorrow.

The MAF will be the correct MAF as I took it off the 92 (Before I pulled everything out, the 92 was driveable, wouldn't run very well with the MAF disconnected, but when I connected it, it ran like a charm, so I know the MAF at least was good a year ago when I pulled the motor), I also tried one out of a Taurus which according to the autowrecker and a few other people, is also the correct MAF, but I had the same problem.

I've also read that a MAF calibrated for 24# injectors will still work for 19# injectors, but I need the sample tube either way, just haven't had the time to run to the performance shop to get the correct one. They're $30

Tomorrow I'll pick up a new set of O2's and order the correct sample tube and see how that goes... I wanna get this thing to the body shop... been waiting so long to get it there... wanna see this thing with the paint I have in mind... looks good in the picture I made, in person might be a different story

7upedition

I's work on getting those o2 sensors in properly seated and getting a MAF cal'd for 19# injectors, try another midpipe that doesn't have the threads all f'd up (if you have one). Sounds like you got it pretty well narrowed down, i'd see what you can do to get that OBDI scanner from your pops this weekend. Good Luck

5.0kidsdad

vristang, I sent you a PM. Thanks, Pat

vristang

I would question the ability to use a C&L cal'd for 24's on a 19lb engine. The difference will be too much for the EEC to compensate in CL, and would cause serious issues in OL.


Regardless,
Please come back and let us know if the O2's and MAF sample tube solve the problems.

jason

Pat - I pm'd you back dude.

Liquid_02

My car has brand new exhaust on it from the headers back to the tailpipes, all brand new ( 3inch LX style tips on a GT... looks sexy ) all custom made for my car, so the H-Pipe is not removeable, so that wasn't an option. I replaced the nuts the guy had on it, and put bungs in it so that was solved there, just the threads on the O2's were bastardized as well.

Stole the scanner and only codes that came up were for the charcoal canister (which I removed) and A/C according to it was on, don't have a relay in the car for the A/C, as by some weird chance... both my fuel pump relay and A/C relay went bad at the same time... go figure... Nothing that would cause it to stall. Whatever, EXTREMELY happy those are the only codes that came up considering the major work I've done to the car.

Bought a new pair of O2's and slammed them in today, still didn't solve the problem.. but I have O2's now anyway. Ordered a sample tube for the 19# injectors as well.. should be here Tuesday, $35 CAD for it. That's gotta be the problem, pretty much the only thing left... I'll tell you how it goes when I get it.

Maybe Ill go try and slam my stock MAF back in this beast and see if she runs... Then I'll be POSITIVE it's the sample tube.. as C&L MAF's as everybody knows use the stock sensor (which is why I decided to get the C&L), so then I'll know if the sensor is good

grabbem88

24 meter would lean out the 19 injectors.

vristang

Maybe Ill go try and slam my stock MAF back in this beast and see if she runs... Then I'll be POSITIVE it's the sample tube.. as C&L MAF's as everybody knows use the stock sensor (which is why I decided to get the C&L), so then I'll know if the sensor is good
[/quote]

I feel like a jack-@$$ for not suggesting trying the stock MAF since you have stock injectors.

That will tell you if the MAF mismatch is causing the issue, or if something else is going on.

Now that you have O2 sensors, remember to disconnect the battery when you install the MAF. This will clear out any adaptive adjustments the computer has made to the injector pulsewidths.

I think you will be running much better with the correct C&L tube.

jason

Liquid_02

Ok, I put the stock MAF back on, and it helped a little. Car is still very rough. I do have a cam in it, but it's only the B303, so it shouldn't be too lumpy at all (still have the stock 1.6 rockers aswell). Also, with the MAF connected, the car wants 25 degrees timing... 15 or lower and it hesitates and wants to stall out... any idea as to what would cause that?

I tried a different scanner with the MAF connected, tried the KOER test but go figure, the battery in the scanner died with 10 seconds left... I did get a "+" symbol before the battery died though, any idea what that means?

Any help would be greatly appreciated.. this is driving me insane... Thanks for all the great replies so far everyone, really appreciate it