No Start 3406b PEEC
Afternoon all, I have been in and out around this site, but never had anything to contribute. Nor have I had any significant issues that I was unable to handle on my own. Until now.
As the title implies, I have a 3406b PEEC that didn't start this morning. It cranked very fast at around 450 RPM, but didn't smoke at all. It didn't even try to catch or anything, just cranked. I suspect that either the fuel shutoff, the PEEC, or something related (wiring) to it is to blame.
The past several days I have been having issues with fuel and throttle response. I would push the throttle pedal to any amount, and it would take half a second to respond and then immediately engage to the amount of throttle requested. It would not ramp up, would not catch part way or anything like that. When it didn't respond, it would simply not respond at all until it did, and at that point respond normally until I came off the throttle again. The gauges, engine, exhaust would not be showing/operating/sound any different from any other time I have owned the truck when it responded properly. When the response was delayed, everything would still be the same, except lack about 30% of its power and smoke noticeably before the turbo came up, and even after, still smoke more than usual. Not a lot, but it could be clearly seen where previously there was essentially none.
Two days ago I was coming down a ramp onto the highway, and the engine would not throttle past 1500 even with the clutch released. It was acting like I had no turbo, smoking far more than usual, but not solid black, and no power. I had a trailer with about 25k in the box, and could not get out of third. (running the original 9spd). I pulled off, shut the truck off and restarted. It started a little rough and would not stay completely steady. It would surge and catch like the throttle was cutting in and out causing a RPM variance of 50RPM. I got it to respond properly with full power again by working the throttle repeatedly and then mashing it down and holding it at the redline for about two seconds several times. It finally got past 1500, engaged the turbo and drove perfectly normal after that for the rest of the day. Yesterday, it started and ran fine for about half the day, then it started having the issue again and doing the modified parked Ferrari tuneup only helped partially. I had to keep doing it though cause otherwise I would lack power and getting back on the highway or up a hill required more power than was available.
The engine has never had any issues with starting, idling or running in any way before. Does not burn oil at all, and is only down about 1/3 from full when it gets changed. Turbo is spinning freely, no mixed fluids and everything checks out properly.
I am experienced with working on vehicles, but have never had to work with the fuel or a PEEC before, so I am not familiar with what the voltages should be and the diagnostic procedures to find a problem with a PEECor shutoff. I believe it is one of those two due to the intermittent nature of the issue and lack of any other problems, lack of exhaust smoke on crank and due to the age, since age has a habit of affecting wiring more than anything. The truck is a 1990 FLD 120 that I have had for about 2 1/2 years. I have never had any issues with it at all, gauges and operation have been perfectly reliable and steady no matter the conditions and load.
There is no data tag of any kind left on the engine, heads or anywhere else, and I cannot see anything stamped into the block on the passenger side at #6 cyl.
I can check for any other numbers and provide pictures of areas if someone needs specific info, visuals or numbers.
Any help or insight anyone could offer on what to check with the PEEC, and what I should find, like voltages, jumper testing of parts, etc, I will be greatly appreciated of it. At worst, a good reliable place to order parts from online that would be cheaper than Mustang CAT here in Houston behind me. I have no issue with changing it over to mechanical and removing the PEEC, but I don't know what else will be required other than getting the linkages for the pedal to the pump, and again any information that can be offered for that, if it comes to it, is greatly appreciated.
I chose this site to post to because I have seen a number of people on here offering good advice, and that understand there is a difference between work that is done right, and work that is merely "in spec", and actually know good knowledge about the old b model.
Apologies for the long post, I can never get my posts to be short and concise, heh.