[kelkell77]

:scream: I have a 1987 GT 5.0L with speed density, stock bottom end, stock cam, headers, 65mm throttle, BBK cold air, MSD ignition, H-pipe no cats.(got the deal of the century, but a headache in the process). My idle surges and hunts continuously for the right position causing the crankshaft timing to jump. It smells like its running rich, and has a hesitation when I apply full throttle when driving(It feels like I have low spot in the HP curve). I have replaced the ECT sensor, MAP sensor, installed a MSD ignition w/ TFI module, 65mm throttle body w/ new TPS sensor. I have followed the procedure for setting the idle, TPS voltage is at .098, there is a thoroughly cleaned IAC, new EGR valve, EGR valve sensor has the appropriate voltage(but has not been replaced),nor has the O2 sensors. I have checked for vacuum leaks, replaced some broken vacuum lines, taken off the upper intake manifold(stock) and checked all lines and clamped them to prevent leaks. So I bought a OBD1 code reader and get intermittent readings. Codes: 14, 21, 31, 33, and 94. 14 is the PIP signal from the TFI(which is brand new), 21 is ECT sensor out of range(which is brand new), 31/33 is a EVP out of range(which is the EGR valve and sensor) half of which is new, but the sensor is reading good voltage!!, and 94 is the ACT sensor(which I have not replaced...yet). All of these codes are associated with the EEC-IV and are KOER(key on engine running). So where do I go from here? Swap out EFI for CARB!!! Just joking, but I would have been done a long time ago!!!!CAN ANYONE POINT ME IN THE RIGHT DIRECTION PLEASE!!!:weeps

 

[green91]

check your timing and check your BAP (barometric absolute pressure) sensor, it can cause what you are experiencing. oh and btw, ect out of range is just your car was not warmed up

 

[davido30093]

You said that you replaced the MAP sensor (BAP?). Try putting the original one back on and see what happens. Also CAREFULLY check the vacuum line going to it to be sure that it is not disconnected or broken ANYWHERE.

 

[tom.moss1949]

Clean up the 10-pin connectors (salt & pepper shacer things) on the intake. Spread the male connectors some and put some fresh grease on the pins. See if that helps - the wiring runs through them and if the connection is poor you get some of the symptoms you are seeing. Is the MAP sensor on it's own dedicated line to the manifold?

 

[GhostDog 5.0]

Check your engine grounds also.

 

[tom.moss1949]

Check your engine grounds also.

Especially the neg battery cable ground in the timing cover - I've seen them corrode severely (galvanic corrosion) on the inside threaded section where you can't see it. I moved mine to the head because mine was corroded and causing start problems.

 

[GhostDog 5.0]

You had to go for the timing cover didnt you :winks

I have mine grounded to the timing cover,where the front sway bar meets the frame, and at the quadshock to frame area.

 

[kelkell77]

Thank you for all the inputs!! I forgot to mention it runs like crap only in the closed loop cycle. As far as the MAP sensor goes I swaped the original back in to try to compare, but it was the same. It has a new vacuum line with a clamp on both ends and is connected to a vacuum tree under the intake. I checked the voltage on the EGR sensor by pushing in the pintle all the way down and the voltage was bouncing everywhere when pushed all the way in! So I replaced that sensor(KOEO passed 11 all the way through), but snapped a bolt off the new egr valve so I went back to the parts store and another will be here by tomorrow),aftermarket go figure! I'm going to change the plastic vacuum lines to the EGR, Smog pump line, and intake manifold to rubber. There so brittle they break off evertime I disconnect them. What was ford thinking!! How do I know if I'm pulling enough vacuum through the EVR, I think that's one of the problems? I am going to check the grounds next as suggested, but I feel it has to do with a vacuum leak of some sort. As for as the negative battery ground(the battery has been recenlty relocated in the trunk) and is grounded to the frame. I spliced off the wire harness ground and attached it to the a/c compressor bracket along w/ my msd ignition ground. Sorry but I am confussed on the engine timing cover ground part that you described!?! I will check the 10-pin (Salt & Pepper) as well. Thanks again and keep up the inputs, I need all the help I can get! Here are some pics of the work in progress, so you know what I'm working with.

 

[nails79]

is your engine grounded to the frame? check to make sure and if not install a good ground strap. also is your car stock? heads, cam? the lack of cats could be throwing you for a loop, your 02 sensors dont know what to do

 

[tom.moss1949]

The O2 sensors are before the cats, so not cats is not a big issue - but correctly working O2 sensors is..........

 

[kelkell77]

Problem Solved

After I fixed all the codes and replaced just about every sensor. The major problem that was effecting my car.... was the damn MSD Ignition box. For some reason it took a crap and was effecting the idle and giving me problems throughout the rpm range. I want to say thank you to everyone who helped me out and for anyone who has that type of problem check out the aftermarket installs first, vacumm lines second, and then your sensors! Because the sensors will make you dig way deep in your pockets!!!!!!!:thumbup

 

[tom.moss1949]

The stock ignition system is good enough for 98% of the N/A street combinations out there.........