Coolcat390 Posted August 6, 2011 Share Posted August 6, 2011 Does any one have a reliable what to isolate which cylinder is missing on a 7.3L? I dont have access to a cut out box. I tryed a KOER cylinder contribution self test and it always says pass. i found some kind of pid in datalogger for each cylinder but dont know what it monitors? Anyone have any ideas? Thanks Tom Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted August 6, 2011 Share Posted August 6, 2011 What year? There's a big difference in op/diag on early vs. late. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted August 6, 2011 Share Posted August 6, 2011 Your post is sadly lacking in a lot of pertinent details. Year? Codes? Noises (does it sound like a helicopter?)? The PIDs you refer to are (ass/u/me mode=on) likely the perdels. Bruce Amacker is our resident perdel expert and has given us much insight into using perdel readings as a diagnostic tool. Perdels only work at idle.... off idle they go to 0% (much like fuel trims on a 6.4). Closer to 0 is better but #8 will usually read a little high compared to other cylinders (even with the long lead injector). High numbers indicate a large change in rotational speed. If the miss is accompanied by the "helicopter sound" you have a bent exhaust pushtube. You can choose which valve cover to remove by removing the Y intake splitter feeding the air boxes (sorry for the Disneyland diesel reference) and feeling for the reversion pulse. Another method of determining a misfiring cylinder is to use an infrared thermometer to check the exhaust manifold ports. Or even , on an IDI, feel each injector to see if any are "hot" and any are "cold". Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted August 6, 2011 Share Posted August 6, 2011 Jim's right, it's probably a late '99 up with perdels, if it's an early '99 it won't have them. Start by reading these and then tell us what it's doing: http://www.forddoctorsdts.com/forums/ubb...=true#Post31686 http://www.forddoctorsdts.com/forums/ubb...=true#Post22830 http://www.forddoctorsdts.com/forums/ubbthreads.php?ubb=showflat&Number=22830&page=1 Good Luck! Quote Link to comment Share on other sites More sharing options...
Coolcat390 Posted August 6, 2011 Author Share Posted August 6, 2011 its a 2001, i already did a manual compression test and all the cylinders are right around 400 psi cold. the concern is its blowing smoke and has no power when towing. the color is a bluish white. already check for the turbo leaking oil internally. i try using the predel but i dont know whats the acceptable limit. i was thinking just pulling all the injectors and bench testing the way the pced tells you to. Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted August 6, 2011 Share Posted August 6, 2011 Did you check FP while under load (50MPH, WOT)? Late 7.3s are notorious for plugging the screens in the tank, restricting fuel on the highway. You must check it at the heads. Your description fits this perfect as they will blow white smoke when fuel is restricted. A 45 degree 1/8" NPT street elbow and a Schrader (Napa 90-290, I think) will make it easier. Forget pulling the injectors and bench testing them, it's a waste of time. Edit- PS How does it run and drive at lower speeds and idle? Quote Link to comment Share on other sites More sharing options...
Coolcat390 Posted August 6, 2011 Author Share Posted August 6, 2011 last time the truck was in it had low fuel pressure. The tank was replace last year but the sender was never replace. I put a new sender, pump and regulator in and got the pressure up to 70psi @ WOT. Im thinkin some of the injector were damage from that. Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted August 6, 2011 Share Posted August 6, 2011 OK... now I'm really fucking confused. Your concern seems to be a lack of power but you are asking about misfire detection... Is the concern a misfire (the first thing to deal with) or a lack of power (something we'd view entirely different)? Quote Link to comment Share on other sites More sharing options...
Coolcat390 Posted August 6, 2011 Author Share Posted August 6, 2011 misfire causing the lack of power Quote Link to comment Share on other sites More sharing options...
Jim Warman Posted August 7, 2011 Share Posted August 7, 2011 Have you tried the buzz test? Don't look for results... listen for them. Backing up a notch... does this "misfire" happen around 1800ish or so rpm when accelerating? Quote Link to comment Share on other sites More sharing options...
Bruce Amacker Posted August 7, 2011 Share Posted August 7, 2011 Can you be more specific? What are Perdels at a hot idle, how does it run at low speeds, how does it pull without a trailer? Does it have dead holes at an idle and lower speeds? We'll be happy to help you out, but you have to feed us pertinent information. "Misfire causing lack of power" is way too broad of a description. It's like going to a medical doctor and telling him you don't feel good..... Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.