Howdy! Hey, Ive got a question for you about your upper plentumn on your EFI. Did you eliminate the EGR? Is there a block off plate used to fill in the gaps? Had some bad luck 2 weeks ago with my efi 5.0,,,,, When I did the conversion, I wired into the stock engine harness,,, As soon as it turned cold outside and got a liitle frost,, it developed a miss,,,, found the #1 injector trigger wire went bad in the plug, fixed it by running another wire,,,, then the IAB started acting up,,, another bad wire from the stock harness,,, So, I sat down and built a brand new harness from scratch. That really is what i should have done in the begining,,, LOL!! I got it back on the kitchen table once again!!! Doing all my prechecks before I put it in the car again. The new harness turned out great!!!! Hope things are going well for ya all!! talk to you soon. ChadS
Hay Chad, Things are going well on this side. Thx. I think you just like testing the miss's patience by putting your harness on the kitchen table every chance you get! lol Yes, I have the EGR eliminator plate (TB Spacer) on my setup (Holley Systemax II to a BBK 78MM TB). see: http://mmb.maverick.to/gallery/files/7/Apr29005_original.jpg Good luck with the demons. I fought 'em for too, too long myself (using stock harness). I know how frustrating that can be. But from what I've seen you tackle and accomplish, you've got the patience to whoop them demons. You might jump on stangnet.com and a few other Mustang sites to see if you can pick up a used Throttle Body Spacer plate (that matches your setup). Here's a quick link to a new one from "Street Beat Cusoms": http://www.streetbeatcustoms.com/formus1950le1.html Good luck and keep us posted.
How do you track down a miss caused by the harness?!? My 5.0 truck is giving me fits. It runs perfect, but gets an intermitent miss under load. I have put all new ignition wires, plugs, rotor, cap, all but coil and module. I have 165 to 180 psi compression. I raised the fuel pressure from 39 to 45 psi. I cleaned and checked the EGR. I found the vacuum line from the coil to EGR was cracked, so I replaced. Did nothing. I have no codes. What else can I do? I used a stethescope and all injectors are ticking... All gauges read fine. About the only other thing I haven't touched was the o2 sensor. Oh, and I replaced the TPS. Dave
That sure sounds like my f150 if you find out why they do it let me know to. What yr is yours. Mine is a 89
Until Chad checks back, the only thing I have to offer is, since you are receiving no codes, you might want to swap out the computer itself (with a known good one) if you have a buddy who will loan you one. As you know, it should record the misfire (no matter what). Actually now that I think about it, the computer could be holding the misfire codes and just not displaying it since it's not a constant miss (multiple mis-fires). A simliar thing happened on my '96 T'bird. The only way to check it was to use a "high dollar" Engine Analyzer (in [font=Arial,Helvetica]KOER mode)[/font]. The "Check Engine" light did not come on (which I assume your's isn't either). In that particular case, the miss was being caused by a faulty camshaft position sensor. From my experience, the EEC's do not often go bad - but, in my group, it's always one of the things we check when trouble-shooting a menacing miss. Hopefully, Chad can shed more light when he checks back in.
My truck pings if I run 87. Usually I run 93. The miss started out few and far between, but it has gotten steadily worse. Today it was missing almost any time the truck was in motion under the accelerator pedal. At idle and down hill, no miss. Almost as if it was running lean. There is no CPS on this engine. It is a 90 model. Dave Edit: I have 18lbs of vacuum at idle, rock steady needle. Very steady motion when throttle is varied... So I don't see any mechanical issue. It has to be a sensor, computer, or injector IMO... Unless the coil is breaking down under load?
possible problem I have worked on many ford pickup trucks and have a pretty wealthy knowledge of fuel injection systems for fords If you look on the driver side in the engine compartment and under the brake booster you will see two connectors round one both brown and i believe blue or white check those connectors for bad or corroded connectors inside the plastic housing. I have had many problems in pickup trucks to be specific they get a miss like you are intermittenly loosing fuel and/or spark. If you are inexperienced in this field you will never find the problem. It took me quite some time to find this bug and it happens alot on ford pickup I believe there is tsb for it unplug both ends and check inside and disassemble the plug and check the connections of the wire and crimp connector for corrosion and pitted areas.
year models problematic year models if remember correctly are mid 80s to mid/late 90s check up under the brake booster the connectors, get brake fluid on them and they get all f'd up and will give problems when you accelarate and are under load. I have experienced this problem myself and i have diagnosed several trucks in those yr models with the same problem there is a tsb for that.
Thanks for the lead!!!! I will check into it tomorrow. I pulled the plugs today when I did the compression check and noticed the rear 2 plugs were different than the foward 6... 6 were gray/tan to gray/rust... looked good, maybe a touch lean. The flat ring on top of the threads, that is exposed to the chamber is black. Not sooty! Just black. Looked pretty good IMO. The rear two were gray/white. They had a rock hard white soot/buildup on them. The insulators were white with solid lumps on the side. One large lump on each plug. The stuff is rock hard and I was afraid I was going to damage the insulator when I was chipping it off. Sandpaper would not scratch it. I just had to crack it off the insulators. The ring on top of the threads was tan instead of black like the other plugs. In case you are wondering, the cleaning and regapping of the plugs did no harm nor good. Same-same... Dave Btw: The lowest compression numbers were on the front 2 cylinders, then the compression got higher as the cylinders went back. Almost identical number to the sister cylinder on the other side of the vee. The rear 2 were the highest compression.
I`ll check that tommorow thanks. As for octane tried that and injector cleaner didn`t help its just so unoften .Different companys gas do make it ping with the same rated octane though. It does feel like its running lean when it does act up.
Well, I found my miss by pulling the spark plug wire off the cap, (while its running) found the dead cyl, or missing cyl. I then took my OHM meter, checked the ohms across the poles, Should check 14 ohms or,,in that area. The injector checked out, so I put the tester on the leads on the injector,, I had power, but no ground. See, the computers,, control the ground to use as a trigger, I guess that way so they are not dealing with high voltage thru the computer itself,,,,,, So,,, I located the wire for #1 injector in the computer plug, sniped it, and run a new wire up to the injector. Problem solved. Another way to check the harness for a short at the injectors is to put a 12v light bulb hooked up to the wiring to the injector. They call that a NOID light,,,, that will let you look at the pulse signal from the computer,, best to compare it to a good injector to tell the pulse pattern. Fords, will run with a bad injector,, its not designed to shut the system down when one goes bad, (like the GM computers do) If you find an injector that has a low OHM reading,,,, that needs to be replaced,, and oh yes,, they can work,, but,,, they can stick open, or closed,,,, Id say closed in the case of the miss,, cause if it stuck open,,, it would run extremely rich on that cyl, and possibly make the other 3 cyls on that fuel rail look lean by the fuel pressure drop from the injector leaking. Bottom line on troubleshooting,,,, get a good digital tester, get a repair manual that will give the specs on the electronic componets and start testing OHM readings. If all the componets test well within the test readings, then the parts are good, and your losing a power lead, or a ground lead from the computer. I found, also, if the idle rpm is set too low,,, it will misfire at idle,,, so make sure everything is set to book specs on idle speeds, plug gaps, etc etc. Some main reasons an efi will have a miss,,,, bad wires, bad injector, spark plugs, or plug wires, or a bad coil. The distributor is the key brain on what feeds the computer on which is what,,,, what cyl, which injector to fire, time open, time closed, and when to fire the spark plug. If the injectors check out, check the wiring to the injector, if that checks out, check the coil, and wires,,, Ive seen the coil wiring corrode,,, or the coil itself can be bad, or starting to go bad,,,,, thats an awful lot of energy they produce,,,,, and thats a big strain on the small coil. ChadS
