need help with 5.0L......
Thread Starter
|
Junior User
Joined: Feb 2006
Posts: 68
Likes: 0
yeah, i have the trucks old cam, but would it work with the roller lifters? plus, im hoping that i can fix the problem without having to change the cam. the truck doesnt run well at startup now either. i have already changed out the o2 sensor. and yes, i am running the trucks intake. what doesnt make sense is the fact that it runs ok, not well, just ok, at a higher rpm. this engine has me scratching my head. any info is very appreciated because i am running out of ideas.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
You just don't seem to get it do you ? You've got a Speed Density EFI system that's programmed for a certain narrow set of engine specs and you're trying to make it run with a completely different engine. It AINT gonna happen. You've completely confused the crap out of the computer. Only 4 things you can do with it: 1. is to swap the cam for a stock type cam for the pickup you have, 2. is to find someone locally who can reprogram the computer for your combo. 3. is to convert it to mass air EFI. And lastly is the carb option. Comp cams has a hyd roller that works with SD systems, if you choose that route.
Lead Driver
Joined: Nov 2002
Posts: 9,558
Likes: 45
From: Concord, NC
A stock mustang MAF cam shouldn't cause these issues with the truck speed density system. I remember a few people running stock mustang motors on the truck EFI without any issues, but it's been a while, so I can't remember exactly who. If it's an aftermarket cam, then that could certainly cause some problems. I would check the MAP sensor for proper operation and to make sure the vacuum hose is still connected. It sounds like it is sending a full load signal, which would cause it to be rich at idle and low rpms, while it would be more accurate at higher load, higher rpm range. I don't think you should start tearing into the engine just yet. Not being able to get any output from the computer concerns me that there is an electronic issue you need to deal with first. Again, a stock mustang cam shouldn't cause the computer to throw a fit this badly.
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
The difference in specs between the truck cam and the Stang cam is HUGE. And as such is exactly like putting an aftermarket cam in there. Expecting the computer to ignore the difference is wishful thinking. Just plain silly to think otherwise.
Lead Driver
Joined: Nov 2002
Posts: 9,558
Likes: 45
From: Concord, NC
Users here have run the stock mustang cam on the truck speed density computer, I know they have. The mustang cam isn't that radical. Sure it is about the absolute limit for what the truck EFI can manage, but I don't think that is what is causing the problems for southernracer.
Another thing that came to mind is to test the vacuum and see exactly what vacuum there is at idle.
Another thing that came to mind is to test the vacuum and see exactly what vacuum there is at idle.
Mountain Pass
Joined: Aug 2005
Posts: 140
Likes: 1
From: Seattle
I would agree with not tearing into the engine just yet. I would want more information before doing that. Definately getting a measurement of what the vacuum is at idle will help alot. My stock 94 5.8L truck at idle gets about 27. I also would spend more time trying to get the codes out of that darn ECU. With the way the truck is running it can't be happy.
Thread Starter
|
Junior User
Joined: Feb 2006
Posts: 68
Likes: 0
FTE Stories
Ford Trucks for Ford Truck Enthusiasts
Top 6 Best Deals Available on New Fords & Lincolns Right Now
Brett Foote
This Hennessey Takes the Expedition Tremor's Off-Roading Capability to the Next Level
Verdad Gallardo
Top 10 Fords at 2026 Carlisle Ford Nationals
Joe Kucinski
3 Best / 3 Worst Parts of Modern Ford Ownership
Brett Foote
10 Amazing Upgrades That Solve Common Ford Truck Owner Headaches
Pouria Savadkouei
Every 2026 Ford Engine Explained
Brett Foote
10 Ugly Ford Trucks That We Still Kinda Love
Joe Kucinski
10 Things Every Truck Owner NEEDS (2026 Edition)
Michael S. Palmer
Rezvani's Latest Post-Apocalyptic Monster Is a Ford F-150 Raptor Underneath
Verdad Gallardo
Hotshot
Joined: May 2003
Posts: 11,141
Likes: 25
From: south louisiana
Originally Posted by EPNCSU2006
Users here have run the stock mustang cam on the truck speed density computer, I know they have. The mustang cam isn't that radical. Sure it is about the absolute limit for what the truck EFI can manage, but I don't think that is what is causing the problems for southernracer.
Another thing that came to mind is to test the vacuum and see exactly what vacuum there is at idle.
Another thing that came to mind is to test the vacuum and see exactly what vacuum there is at idle.
Lead Driver
Joined: Nov 2002
Posts: 9,558
Likes: 45
From: Concord, NC
There are too many other possibilities that don't involve tearing the engine apart that I really believe should be checked first. Once all the other avenues are tested and checked, maybe then think about swapping the cam, but for the amount of work involved, do all the simple things first. Until we know things like idle vacuum, computer codes, etc, I don't think it's safe to swap the cam and then be disappointed if it runs the same with the truck cam. I still don't think that the mustang cam is causing these problems. It should have been evident from the very first start. From what I gather from southernracer's posts, it just started this after driving for a while.
Try resetting the computer - if it runs as bad as it does now, look for something that changed after your initial drives where it ran fine. How are you pulling the codes? You'll probably have to use an analog voltmeter on the 86 because I don't think Ford wired a check engine light in the dash on those years.
Try resetting the computer - if it runs as bad as it does now, look for something that changed after your initial drives where it ran fine. How are you pulling the codes? You'll probably have to use an analog voltmeter on the 86 because I don't think Ford wired a check engine light in the dash on those years.
Thread Starter
|
Junior User
Joined: Feb 2006
Posts: 68
Likes: 0
Hey yall, thanks for the help. i finnaly got the engine runnin right. it wasnt the cam, it wasnt the computer, and it wasnt the speed density. turns out the MAP sensor on the passenger side firewall awsnt getting any vacuum. i had to take it to a buddy of mine who works as a mechanic everyday, instead of like me who only works on the weekends on my own stuff, and he knew whta the problem was instantly. i thank all of you who helped with suggestions. the truck had me at the end of my rope! almost started to like chevy's
. thankfully i got back in the right state of mind. i say again, thank you to everyone who gave suggestions.
. thankfully i got back in the right state of mind. i say again, thank you to everyone who gave suggestions.
Lead Driver
Joined: Nov 2002
Posts: 9,558
Likes: 45
From: Concord, NC
One of the easy things to check first (like I mentioned in post #19)...glad you didn't swap the cam. I agree with baddad to check the plugs, as a precaution, but I doubt there will be anything out of the ordinary.
Junior User
Joined: Feb 2006
Posts: 70
Likes: 0
i have a 94 f-150 with a ho motor from 86 gt mustang and i have had to replace the 02 sensor three times but im running headers and welded a 02 bung in my header on pass. side just before collector. prob. your 02 sensor.borrow a code scanner and check it you say that the computer did not send any codes the ground is prob. not good there clean up the grounds for the computer on fenderwell and try again. also there is a differance if its multi port efi or secquencal cant spell but you have to change i think 4 pins at the computer to make it run right there is an articial about it i found the link from this site. hope this helps
Last edited by dv_shane; Mar 25, 2006 at 06:05 PM.
Thread
Thread Starter
Forum
Replies
Last Post