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Hi guys! My 17yr old just bought himself a 1993 F150 with an EFI 5.8. The motor was really recently rebuilt and runs nice, EXCEPT at idle. It will constantly surge and bog, until you get on the fuel.
I took it to a shop for diagnostics and they recommended an aftermarket EFI .. OR… to look into a tuner for it.
the reason it idles poorly is the previous owner installed a Melling Stage 2 cam (24225) this is why the shop made the recommendations.
it has no vacc leaks, a new distributor, wires, plugs, IAC, etc. (we recently replaced the IAC as it was stuck and it runs worse now! Before it would idle very rough until it was warm, then it was reasonable, even in gear. But now it won’t idle even when warmed up or in neutral)
MY QUESTION… can anyone here recommend a specific tuner so we can get this thing to idle without surging Bad??!!
Aftermarket EFI isn't really a cost-reasonable solution, especially considering there's really not anything wrong with the EFI hardware already on the engine.
The PiMPx is a computer replacement, that plugs into your factory harness.
The Quarterhorse and TwEECer are both options, and plug into the factory ECM, and allow you to do tuning.
I'm personally inclined towards the PiMPx, but that's just because I have prior experience with MegaSquirt based ECU's, there are a number of fellows here that have had good success with the QH or TwEECer
Aftermarket EFI isn't really a cost-reasonable solution, especially considering there's really not anything wrong with the EFI hardware already on the engine.
The PiMPx is a computer replacement, that plugs into your factory harness.
The Quarterhorse and TwEECer are both options, and plug into the factory ECM, and allow you to do tuning.
I'm personally inclined towards the PiMPx, but that's just because I have prior experience with MegaSquirt based ECU's, there are a number of fellows here that have had good success with the QH or TwEECer
Thanks fleet! If you don’t mind, so then would he need to spend the full $1,000 on the full Pimp X kit? *Linked below
Or might there be an even more cost effective option?
No, he'd need the whole setup. The Quarterhorse and TwEECer are less up front cost, but quite different, and from what I can tell, look more complicated to tune with.
Is the Truck an Automatic, or a 5-speed? If it is the 5 Speed, you can save a little money, with the basic PiMPx, if it's the E4OD Automatic, you'll actually need to spring for the PiMPxshift, because you've got to be able to control the transmission as well.
The PiMPxs is overkill for your application, in my opinion, and it would require changing the injector harness/injector wiring to make the sequential fire work.
No, he'd need the whole setup. The Quarterhorse and TwEECer are less up front cost, but quite different, and from what I can tell, look more complicated to tune with.
Is the Truck an Automatic, or a 5-speed? If it is the 5 Speed, you can save a little money, with the basic PiMPx, if it's the E4OD Automatic, you'll actually need to spring for the PiMPxshift, because you've got to be able to control the transmission as well.
The PiMPxs is overkill for your application, in my opinion, and it would require changing the injector harness/injector wiring to make the sequential fire work.
Thanks for that clarification!!
and yes, it's the E4OD Automatic.
I really appreciate your prompt replies! I think I should be good from here, unless there’s any other advice you might have? Otherwise, again… Much appreciated!
That cam is not really suitable for the motor so why don't you just change it to somethinng that is more suitable like the Comp 35-255-5, that's a couple hundred bucks plus some gaskets I don't see a tuner solving the issue it has now, in general these "performance" cams require a higher idle speed to overcome the unstable vacuum generated at lower idle speeds, but if you do that the torque converter will begin to catch and push the vehicle. And... the lower vacuum signal will result in higher fuel consumption overall because the factory SD EFI system is referenced to manifold vacuum, this is why "EFI friendly" cams are always recommended when upgrading these motors, these do deliver increased performance over stock without upsetting anything else.
When they did the cam, did they add MAF?
As mentioned above, a quarter horse can do the job, but if it is still Speed Density, you would be much farther ahead to just put the right cam in it. If it is MAF, you probably have a bit of research to do before doing much of anything. One thing you really need to be sure of is the computer and it's current tune/strategy.
There will/should be a tag on the connector of the computer with everything you need to know.
When they did the cam, did they add MAF?
As mentioned above, a quarter horse can do the job, but if it is still Speed Density, you would be much farther ahead to just put the right cam in it. If it is MAF, you probably have a bit of research to do before doing much of anything. One thing you really need to be sure of is the computer and it's current tune/strategy.
There will/should be a tag on the connector of the computer with everything you need to know.
I see it has been MAF converted. Almost looks as if this 92 with 93 engine already had it. I’ve attached a pic of the MAF. also, the connector has a few #’s. Can you guide me which I should reference? Thank you! MAF
That cam is not really suitable for the motor so why don't you just change it to somethinng that is more suitable like the Comp 35-255-5, that's a couple hundred bucks plus some gaskets I don't see a tuner solving the issue it has now, in general these "performance" cams require a higher idle speed to overcome the unstable vacuum generated at lower idle speeds, but if you do that the torque converter will begin to catch and push the vehicle. And... the lower vacuum signal will result in higher fuel consumption overall because the factory SD EFI system is referenced to manifold vacuum, this is why "EFI friendly" cams are always recommended when upgrading these motors, these do deliver increased performance over stock without upsetting anything else.
I'm beginning to feel this may be the best route. Cam and lifters as well I presume? Question… why do you feel a tuner would not resolving the issue? Thanks again gentlemen!
I see it has been MAF converted. Almost looks as if this 92 with 93 engine already had it. I’ve attached a pic of the MAF. also, the connector has a few #’s. Can you guide me which I should reference? Thank you!
Oh, I don't see a MAF Meter anywhere in any of those pictures. I do see a MAP Sensor, which is what I would expect to see on a Stock Speed Density EFI setup, which was stock on a 92 or 93.
The MAF will be in the intake tube between the Air Filter and Throttle Body, if it exists.
A tuner very well could resolve the issue, how ever it would be WAY more costly to go that route if you do not absolutly have to.
HA beat me to it SFaulken, They may still have done the MAF, but I am doubting it with the way the harness looks to be stock. One more photo of the intake from the filter box to the throttle body will tell that story.
If your not wanting to learn tuning, swap out the cam.
If you want to learn tuning and have the money PimpX.
If you want to learn tuning and find PimpX is expensive, get a QueartHorse ($250), then an online tune from Decipha @ efidynotuning.com (~$400).
Alsoo....there is this nifty little part that the Mustang guys used to use to adjust the IAC mechanically/manually without a tuner:
Ford Idle Air Control Adjuster 5.0L 1986-1993 Ford: F2PZ-9F939-A
The purpose was to stop 'coke' build up in the throttlw body, but can be used to adjust IAC to maintain a steady idle with a non-stock camshaft.
I have one, haven't installed, but I like tinkering, another thing to tinker with.
Not sure if anyone cam chime in as to whether or not this will work for you application.
Can still be found NOS.
Oh, I don't see a MAF Meter anywhere in any of those pictures. I do see a MAP Sensor, which is what I would expect to see on a Stock Speed Density EFI setup, which was stock on a 92 or 93.
The MAF will be in the intake tube between the Air Filter and Throttle Body, if it exists.
Ah, yes. No, I do not see a MAF meter. Can you? Thank you guys again. It’s been 20 years since I’ve worked on one of these.
If your not wanting to learn tuning, swap out the cam.
If you want to learn tuning and have the money PimpX.
If you want to learn tuning and find PimpX is expensive, get a QueartHorse ($250), then an online tune from Decipha @ efidynotuning.com (~$400).
if you go the QH way, do the research on your EEC/ECU to make sure it is supported. I had to learn this lesson the hard way. However, once you figure out what it is you have and where you want to go, the QH is a very viable option.
It has taken me several months, but yesterday, I got it to pass emissions on the first try (Very satisfying). I went from a 5.0 to a 5.8 with MAF update and a odd ball cam. It was the cam that started me down the tuning path, and while I was meandering around lost in the whole business, I ended up with a MAF as well.
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