1993 F250 7.5 / 460 5-speed manual

I am excluding the manufacturer of the mass air conversion kit I used because it is not relevant, and I do not want to speak poorly of any person or company before I get some feedback as to whether or not they are being truthful.


Since my mass air conversion, I have had a host of issues (mostly coincidental). The only current issues are that the pickup does not go to high-idle upon cold start, it stumbles under load, and I have trouble codes for thermactor issues (air injection system has been deleted, but solenoids were left in place). Everything I have read on this site says that removing air injection should not cause any issues.

The manufacturer of my conversion kit has told me repeatedly that not using a k&n conical intake is causing this. I opted to use a factory intake from a mass air 5.0 f250 to try to keep it looking factory, and because "Project M.P.G." found their best results with a factory-style intake and a k&n drop-in filter. However, the computer used for my mass air conversion CAME FROM A MASS AIR 5.0 MUSTANG.

My question is whether or not a different intake could be causing my issues. The whole reason I converted to mass air was to optimize fuel economy. The premise and appeal of mass-air is that it adjusts fuel based on how much air it measures; shouldn't it be able to adjust its air:fuel mixture to any intake? The Ford intake was good enough for factory 5.0 mass air, why wouldn't it be accurate enough for me? If the intake is the issue, wouldn't an aftermarket intake on a factory mass-air 5.0 also throw the computer off? Obviously, there are plenty of mass-air 5.0 Mustangs and F-series pickups that have used different intakes without issue.

Here is an excerpt from my latest email to the manufacturer:

"I am gladly willing to purchase your intake and TAB/TAD delete kit if you will refund them and pay return shipping if they do not solve my issues. That to me will provide a fair situation of whether or not your proposed, though rather expensive, solutions will actually help my problem, and it will show me that you aren't suggesting those fixes just to get more of my money. I did tell you the intake I planned on using when I spoke to you before my kit was shipped, and you said you would provide me with a different style of meter to connect to a factory-style intake."

Am I being unreasonable? I didn't pay the price of the kit to make my pickup run WORSE!

Give me you thoughts, and thanks for reading.

- Joe

The mass air conversion kit manufacturer also sells k&n conical intakes, so I'm suspicious that he is trying to get me to buy more unnecessary stuff from him.

 

The intake isn't your problem.
That is the best option for a MAF conversion but in your case it won't work any good all without a chip/tuner or a scaled meter/injector set. Do you have one of those currently?

 

The meter is said to be calibrated for my application. Could the thermactor trouble code be causing problems? Air injection is gone and the cat is gutted because it fell apart and plugged my exhaust.

 

No air injection is a common delete that doesn't affect engine operation and the Mustang PCM doesn't do the extreme high cold start idle routine the truck PCM does. Are you using blue top 24lb injectors with this? The PCM will take a bit of time to adjust it won't run perfectly right off the bat(for that you need a custom tune), so it should improve the more you drive it.

Does the truck have a full exhaust on it and where are the O2 sensors installed?

 

Are you getting any other any codes from the PCM you installed? Might it be bad? Is it OBDII? OBD1 should have a self check pass code right?

 

Did you ever replace the fault with the EGR valve?
I saw in your previous post that was or could be the reason for poor fuel economy in the first place.

With your 5.0 MAF on 460 conversion, I think 3 key components need to be matched: ECU, injector Sizes, and MAF.
Can you confirm that the ECU was programmed for the MAF you have, as well as the injectors that are in the 460?

 

The injectors are factory blue ones. The pickup has full factory exhaust with the exception of the gutted cat. The "passenger" oxygen sensor is located in the oem location right before the cat, and the driver oxygen sensor is located on the driver side collector.

The codes I got last I checked were 311, 314, and 553 for thermactor-related stuff, 563 and 564 for Mustang electric fans, and 334 for EGR position sensor. It is OBD1.

I replaced the EGR valve, but since I am still getting code 334 for EGR position sensor voltage being too high when the computer is calling for the valve to be closed, I will likely replace the EGR position sensor next. I can only confirm the programming/calibration to the extent that I was told by the kit manufacturer it is set up for what I have.

Thank you for the feedback and suggestions thus far. Unfortunately, I don't have room for a fourth vehicle in my driveway, so my F250 is up at my parents' house right now.

- Joe

 

OK so you have an aftermarket MAF meter with a scaled sampling tube for 24lb injectors. What you need to do is verify that the meter has the correct sampling tube installed, sometimes they are color coded to make them easier it identify others may be numbered. Let us know what brand the meter is supposed to be and have a look to see if there is anything to identify the sampling tube in it. This device is the most important part of your setup right now and it must be right, if you accidentally got a meter with the wrong sampling tube the computer fuel curve will be all wrong.

 

I will go get my pickup tomorrow. I currently have two projects and one newer vehicle. I work on one project until i get sick of tinkering with it, then i switch to the other, and the process repeats. Right now I've been enjoying my Bronco II so I haven't been tempted to get to work on my F250! I know that severely limits my helpfulness in YOUR efforts to diagnose MY VEHICLE. Nevertheless, i very much appreciate all the time and energy everyone on this site has spent educating people like me. You are an awesome bunch! I literally work on PLC's for a living, which is exactly what our ecm's are, but knowing how a PLC works is pretty useless without knowing the sequence of control, and that's where this site's knowledge is invaluable.

Sorry for writing a novel, but it consistently blows me away the willingness to help strangers. Y'all are awesome.

- Joe

 

Sorry to hear about your troubles. It's certainly frustrating when something you spent a lot of money on doesn't work as you expected. The different intake tube/filter may or may not throw off the MAF reading depending on how they created the MAF transfer function and where in the intake pipe the MAF is located, as well as what kind of MAF it is.

If you can get the company to let you return the conversion kit then I can get you a modern standalone ECU that plugs into your stock harness and is likely cheaper than your MAF conversion kit while being fully tunable with self learning capability, has closed loop fuel control with a wideband o2 sensor so it can constantly adjust your AFR for optimum fuel economy, allows you to target a leaner AFR under cruise conditions for better MPG, allows unlimited modifications, etc. They likely won't let you return it and I understand you've got a lot of money wrapped up in it so this option may not be possible but it's something to think about.

 

I know this is a few months old but I would be interested in knowing more about this. Just picked up a 92 f350 460 and started gathering parts to do a conversion, A9L computer, maf injector harness. Was going to repin the truck harness to match the mustang computer and to switch injector firing order. But if the price is right and does not require as much work I might just go that way.

 

The PiMPx/PiMPxs/PiMPxshift are listed here: https://www.stinger-performance.com/...ine-management

The PiMPx is for batch fire applications (like your truck) with manual trans or non-computer controlled auto transmissions.
The PiMPxs is for sequential applications (like your truck IF you add the extra injector wires to the ECU) with manual trans or non-computer controlled auto transmissions.
The PiMPxshift is for batch fire or sequential applications with computer controlled transmissions.

 

With my mass air conversion experience, I would NOT do it again. I have honestly considered reinstalling my old system. Not all of my issues are because of my conversion, but my mass air conversion definitely amplified every issue I might have had before, and probably added more issues.

I spent $800 just for the kit, plus $120 to have a second bung welded into my exhaust, plus..... you get the point. The list is still going on. Next will be Moates, then wideband, and so on just to get the thing running right.

I don't know what you are debating in your head, and I don't mean that rudely at all! I have different opinions depending what you are trying to decide! I would choose mass air over speed density. I would choose a diy conversion kit over purchasing a conversion kit. I would run a stand-alone ECU kit over purchasing a conversion kit.

You are already ahead of me because I couldn't find an A9L for less than ebay price. If I were you, I would try to find injector plugs and Ford computer pins and crimper.

Best of luck, and please keep us posted!

- Joe