OK, so this all began with a no-start condition. The would turn over but would not even try to fire. I suspected the TFI module and I happened to have a spare re-manufactured distributor I picked up from eBay to have on hand. I swapped the distributor and TFI module and the car now started. Unfortunately the tach was acting very erratically and the car was pretty much un-driveable. It bucked and missed all over the place.
The next day I went to O'Reilly and picked up a new TFI. Installed it on the original distributor, as I did not really trust the $25 reman, with the supplied pasted and started the car. Idle and tach were much better and the car drove fine, until I tried to go WOT and it fell on it's face and would not rev past 3500ish.
At this point I'm thinking I have something wrong with the distributor, so I order a distributor, TFI and coil from Performance Distributors. I swap everything over and I'm still having the same problem.
Now decided to remove the SCT chip thinking something may have gone wrong there. Nope. Same result. Car struggles to get past 3500 RPM under part throttle, WOT and free revving. I do notice that the tach starts to act crazy when I reach around 3500 rpm.
I don't know what else to replace at this point. Any ideas?
Double check the basics. Start with cap and rotor, any rust/corrosion? Spark plug wires arcing? Are your spark plugs in good shape and gapped appropriately? Do you have enough fuel pressure? Is your air filter clogged? Are your injectors clogged? Is your fuel filter clogged? And last but not least, correct firing order?
Code reader should be here today. I'll try and figure out how to get my fuel pressure gauge on there, the port is currently being used for the fuel side of my nitrous kit. Yes it's a 93.
Cap and rotor are brand new, came with the brand new distributor. I'll try and replace the fuel filter this Saturday, but I'm leaning more towards an electrical problem as this began as a no-start issue and once the TFI was replaced it started, but just would not want to run in the higher RPM range. I've had low fuel pressure issues with another car before and this feels completely different. Also the tach being erratic in the higher RPM is steering me towards some sort of electrical issue.
Parts cannon. Already loaded and fired. New parts include:
Distributor
TFI module
Cap
Rotor
Coil
I'll follow up with any codes I can get from the car. It does idle and drive great as long as I'm not trying to get above 3500 rpm.
I thought that as well and first thing I checked was the inertia switch. That was fine and I could hear the fuel pump prime when I turned the key. I guess I could hook up my LM2 wideband and see if it goes stupid lean at high RPM. I will still double check fuel pressure as I can since the pump is 14 years old. The engine won't rev past 3500ish with no load, so I should see a considerable fuel pressure drop if that is the case.
The orange wire with the ring terminal is the HEGO ground,not the EEC ground.The 10ga wire that comes off the neg battery post that bolts to the driver fender apron is the EEC/ECU ground. The o2 sensors wont output correctly if the HEGO ground wire is loose/disconnected.
Every one of the sensors that use the black/ white signal return ground wire (which comes from pin 46 and is tied into/connected to the EEC ground *on the ECU circuit board* at pins 40 and 60) wont function correctly if the EEC ground wire is loose,corroded or disconnected at the fender apron and at the two black tubular plugs that you snap together.However,when the EEC ground does have an issue,you'll normally have codes present for all of those sensors also.
The following list is the main grounds:
1) Primary Ground=
Neg battery post to engine block,to the left of the oil filter
2) Secondary Ground=
Driver cylinder head (rear) to driver fender apron
3) EEC Ground=
Neg battery post to driver fender apron + connection at the two black tubular plugs
4) EEC Case Ground=
EEC housing to the passenger side floorboard
5) HEGO Ground=
Orange wire w/ ring terminal to a lower intake studded bolt (rear)
Grounds 1-3 listed above are the grounds that makeup the ground loop.
Double check the ECU ground wire at the back of the intake manifold. Orange wire should be grounding at the lower intake/head near the firewall on drivers side. May as well double check all grounds, clean and reconnect. Don't forget to check the other ECU ground in the passengers kick panel.
The orange wire with the ring terminal is the HEGO ground,not the EEC ground.The 10ga wire that comes off the neg battery post that bolts to the driver fender apron is the EEC/ECU ground. The o2 sensors wont output correctly if the HEGO ground wire is loose/disconnected.
Every one of the sensors that use the black/ white signal return ground wire (which comes from pin 46 and is tied into/connected to the EEC ground *on the ECU circuit board* at pins 40 and 60) wont function correctly if the EEC ground wire is loose,corroded or disconnected at the fender apron and at the two black tubular plugs that you snap together.However,when the EEC ground does have an issue,you'll normally have codes present for all of those sensors also.
The following list is the main grounds:
1) Primary Ground=
Neg battery post to engine block,to the left of the oil filter
2) Secondary Ground=
Driver cylinder head (rear) to driver fender apron
3) EEC Ground=
Neg battery post to driver fender apron + connection at the two black tubular plugs
4) EEC Case Ground=
EEC housing to the passenger side floorboard
5) HEGO Ground=
Orange wire w/ ring terminal to a lower intake studded bolt (rear)
Grounds 1-3 listed above are the grounds that makeup the ground loop.
I did a little more today. I would have done more, but I do have a mild fever and it's extremely hot in Texas.
I changed the fuel filter, but that did not make a difference. I also ran the codes and got the following:
KOEO:
10, 11, 33
KOER:
21, 30, 44, 94
I don't have anything hooked up to the smog pump so that would explain the 44 and 94 codes.
The tube coming off of the back of the heads is not plugged very well and I have a small exhaust leak there, could that be what's causing code 33?
The car was not fully at operating temperature so I wonder if that is why I got code 21.
I'll check the wire and spark plug on cylinder 3 for code 30. I don't know how much I trust this code as I did not snap the throttle above 2500 RPM.
A friend of mine suggest cleaning the MAF and checking the piping for leaks. I do have a C&L, I know it's not the favorite around here, but it came with the car and was working fine.
I'll also try to figure out how to get a fuel pressure gauge on the rail. Maybe it will screw onto the fitting for the nitrous line, if not I need to order a replacement schrader valve. The fuel pump probably has less than 20k miles on it, but it's about 14 years old.
Would I have gotten more codes if my grounds were bad?
I know in the GM world when the MAF is disconnected the computer switches over to speed density. Is that the same case with the EECIV? If I were to disconnect the MAF plug, would it just go in speed density mode? If that is the case I'm sure it would run really rich as I have 24 lb/hr injectors, but it would at least be able to rev above 3500 RPM smoothly. This would just be briefly in order to test the MAF. I've already used the MAF cleaner, but have not fired up the engine yet.
Another thing to check is meter the red/lt blue wire at the distributor. It should only have 12v while cranking. If it has 12v in the run position it will cause the issue you’re having because it’s retarding timing.
I tested the fuel pressure and it does not drop. It was at 50 psi with the vacuum line off, so I adjusted it back to 39 psi.
Cleaning the MAF did not make a difference either. Here is a video of going WOT in 3rd gear, as you can see it does not really want to pull any higher than 4k and the tach starts to freak out.
Could I set my timing to 32 BTDC and leave the spout out? If I'm not getting any advance this should point it out?
Yes that’s the same wire. When you check timing you’ll see it continue to retard as rpm increases. If it does I would dig a little deeper. 5 volts may cause the issue. My friends car had this problem and this was this issue.
Pull the spout. Shine the light. Rev the motor slowly and see what it does. It should absolutely not be retarding. There are a few different ways to approach this. If it retards towards 0 degrees, clip the red/lt blue wire at the distributor and see if it’ll rev past 3500. You don’t want to clip it and try to start the car. Start the car first. The function of this wire is to retard timing during cranking. Or clip it and run a temp wire from the solenoid.
I would rather not clip the wire if at all possible. Where does it come from? Does it split from the ignition switch to the starter solenoid and distributor?
That “signal”is the 5 volts. That wire should have no voltage with the key in the run position. The only way around not cutting it is to isolate the circuit associated with that wire. Which can be daunting. There is the ignition switch, neutral safety, starter solenoid and whatever else is in the loop. I get you don’t want to cut the wire. If you were any closer I’d come help however 3.5 hours is a hike.
I understand that we are far away, but the gesture is always nice! I found this diagram and I have a question. If I unplug the clutch interlock switch, that should kill the voltage to the red/light blue wire? And if that does kill the voltage, would a new clutch switch solve my problem? I should also try to remove the wire from the starter solenoid first and see if that helps at all.
Not necessarily. That wire could easily be inducing voltage from the wire next to it. If the wire has been flattened or the insulation is deteriorating in a section. These cars are old and some have been in piss poor environments. Not saying yours has. Indy has the right train of thought by not throwing parts at it. This will only piss you off more. You’re on the right track. Isolate a little at a time. Start by unplugging each part one at a time and retest. Start on one end of the circuit either the ignition switch or solenoid and work back. You need to figure out which red/lt blue goes to the distributor after the clutch switch. There are several under the dash.
No updates today, I'll have some time tomorrow to work on it more. I'll probably unplug the clutch switch connector with the red/lt blue wires after I start the car and see if that solves the issue. It will at least tell me if voltage is being picked up somewhere down the line. If that is the case I'll probably cut the wire from the distributor and run a jumper to the wire on the starter solenoid. I'll tidy everything thing up when I do my H/C I/ swap later this year and have better access to the harness so I can locate where the problem is and repair as necessary.
The old Ford Flat Heads with the Stromberg 97's were never this much trouble and they sounded a whole lot better with just a couple of Smitty's.
Cars are to complicated today to be any fun.
You spend all your hard earned money and patience just to make them run.:grin2:
I had the same issue on my first supercharged car? Is your car supercharged or have high compression? Maybe a car that should make over 350 rwhp? If so you need an after market ignition box. MSD boxes work great. My car used to be a nitrous car then I bought a blower. Car wouldn't go past 3,500 rpm. Installed a box and 7,000rmp all day long (pms and many add ons @ that time)
I know yours sounds electrical, but when mine wouldn't rev past 3500, I had a broken inner valve spring. I spend days looking at ignition and fuel. Could be worth it to check your valvetrain.
It's fixed for now. I went ahead and snipped the red/light blue wired and spliced it with the starter solenoid wire and all is working well now. I'll find where the break in the wire is when I do replaced my heads and I'll plenty of room to dissect the harness.
I really want to thank everyone that went out of their way to help me fix my car.
Just so I (and probably some others) understand - the red/light blue wire is the "start signal in" on the TFI, correct? And yours was seeing voltage all the time, so it thought it was in start mode (I presume that means retarded timing and maybe a limiter or something)? I don't see how DC voltage can get induced into another wire - it takes AC voltage (collapsing fields and all that) to induce a voltage from one wire to another. More likely you have a bad switch or something.
Either way, good find and thanks for sharing the info. I haven't run an EEC IV for years, but I'm sure this helps someone down the road.
You are correct. There are two red/light blue wires coming from the clutch switch, one goes to the TFI and the other to the starter solenoid. Somehow the wire to my TFI was showing 5 volts with the key in the run position. I already replaced the ignition switch thinking that could be sending voltage to the wire, but it did not make any difference. I was not getting any voltage to the wire on the starter solenoid with the key in the run position. Also I could not turn the engine over without pressing the clutch, so I'm guessing my clutch switch is fine and I must have two wires that rubbed themselves together causing voltage to get to the red/lt blue wire.
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