olaaf Posted September 17, 2013 Share Posted September 17, 2013 After an 8 month build process, I’ve finally gotten the car rolling again. I drove it for the first time today around a little bit and then to my dyno appointment. It was misfiring on the highway and it idles roughly. Every 5 seconds or so it drops 50 RPM for a few seconds and then it regains it. On the dyno, it made very little power and misfired like crazy. On one of the pulls the computer threw a cyl 3 misfire code. Afterwards, thinking bad coils, I tested 8 known good coils, but same issue. I have 8 new motorcraft sparkplugs, the cold air kit, tune. I also put in a fresh fuel filter. Thinking it’s still related to ignition, I disconnected the ignition capacitors/condensers. Same issue. I’m kinda hoping it’s something like “oh, when you rip out all the airbags and fuel inertial switches and do basic race prep, you need to watch out for ”x”..” Any pointers out there? Video of a run down an alley with the sound Thanks olaaf Quote Link to comment Share on other sites More sharing options...
suck fumes Posted September 17, 2013 Share Posted September 17, 2013 Check the camshaft position sensor and crank angle sensor. Both of those will cause it to backfire and miss like that. Those two sensors are still the weakness on all the 99 spec miatas too! Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 17, 2013 Share Posted September 17, 2013 give me all the codes it has thown. did or have your tried a return to stock on the controller into the pcm and tried to drive it ? Quote Link to comment Share on other sites More sharing options...
ILIKETODRIVE Posted September 17, 2013 Share Posted September 17, 2013 have you tried a return to stock on the controller into the pcm and tried to drive it? This. Don't jump to blaming a failure when prior to making changes there were no failures. Remove the unknown (new/replacement parts) and go back to the known. Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 17, 2013 Share Posted September 17, 2013 give me all the codes it has thown. did or have your tried a return to stock on the controller into the pcm and tried to drive it ? Also , check your grounds. at the engine block and at the battery in the trunk . Bad grounds can do crazy electrical stuff. Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 17, 2013 Author Share Posted September 17, 2013 have you tried a return to stock on the controller into the pcm and tried to drive it? This. Don't jump to blaming a failure when prior to making changes there were no failures. Remove the unknown (new/replacement parts) and go back to the known. Yes, i re-installed the stock airbox and tune, same problem. i stopped short of putting the old plugs back in, haha, one had broken during extraction. ugh. Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 17, 2013 Share Posted September 17, 2013 (edited) no codes then ? check those grounds. at the battery, passenger shock tower. passenger engine block mount and passenger front radiator support. then go check the ground at the rear trunk next to the fuel pressure driver module. Edited September 17, 2013 by Guest Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 17, 2013 Author Share Posted September 17, 2013 give me all the codes it has thown. did or have your tried a return to stock on the controller into the pcm and tried to drive it ? Also , check your grounds. at the engine block and at the battery in the trunk . Bad grounds can do crazy electrical stuff. grounds are solid, i checked that first. It throws a cruise control multifunction switch code. Once only did it throw the misfire code on cyl 3 during a pull, but after a 20 mile drive back to my garage there were no codes. of note, i use the kill switch to shutdown the car. problematic for the advanced PCM? i wired the single pole kill in such a way to discharge the alternator current to the battery. i have the FSM and will go through the "no code" diagnostics procedure tonight- is there a scanner that will read PID values i can get at a local store? the ford tuner doesn't tell me much.. I'm supposed to load up to get to lime rock for a shakedown on Wednesday, lol- guess i won't be sleeping soon- thanks for the help Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 17, 2013 Author Share Posted September 17, 2013 no codes then ? check those grounds. at the battery, passenger shock tower. passenger engine block mount and passenger front radiator support. i will pull them, sand down the metal, and re-torque for sure- thanks. Quote Link to comment Share on other sites More sharing options...
99cobra2881 Posted September 17, 2013 Share Posted September 17, 2013 Dirty mass air flow sensor? It wouldn't explain the miss but it could help with the idle issues. Quote Link to comment Share on other sites More sharing options...
suck fumes Posted September 17, 2013 Share Posted September 17, 2013 Cam sensor! Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 17, 2013 Share Posted September 17, 2013 to me it's doubtfull it's a sensor of any sort since it's not throwing codes. still going with grounds and or a electrical problem. how is your battery and alternator charging ? long shot for sure but you didn't leave your battery hooked up with your pcm and all when you did the welding for your cage did you ? Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 17, 2013 Author Share Posted September 17, 2013 i doubt it's the cam sensor too, that only controls the sequential fuel injection. i'm pretty sure the computer would fall back onto batch injection from the crank sensor. I know on these fords the crank sensor is a variable reluctance type. simple and hard to break. charge is good-13.6v when running. battery and computer were not connected when welding, i made sure of that. i'm starting to lean towards grounds as well, it's one of the few things i changed around (moving some wires here and there). i'll find out tonight. Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 17, 2013 Share Posted September 17, 2013 another long shot: your oil temp switch plugged in at the oil pan ? phaser will not work properly if it's not plugged in....usually throws a code though and operation is fine just no power above a certain rpm. seen this made before with aftermarket pans being installed.... pcm wants a temp for operating conditions to advance phasers. still thinking ground though...... Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 18, 2013 Author Share Posted September 18, 2013 oil temp is plugged in. No luck on the grounds, cleaned and re-tighten all of them, and ran jumper cables around as well. I did pull each fuel injector while looking at the short term fuel trims and say the computer richen the corresponding bank, so all the cylinders are combusting. I think I’ll try pulling out the evap and egr system and inspecting the pins on the PCM. I did take the PCM out to get the serial for the cold air kit. Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 18, 2013 Share Posted September 18, 2013 is the miss all the time or load based ? Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 18, 2013 Author Share Posted September 18, 2013 is the miss all the time or load based ? all the time. it idles roughly- the engine rocks back and forth on the engine mounts. 750 rpm or so. At very light throttle under load, 3rd gear on the road i can feel it misfire/buck slightly. Pulling each injector makes it slightly worse. Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 20, 2013 Author Share Posted September 20, 2013 An update, while I’ve not fixed the problem I have more data. After a 25 minute session at lime rock heavily misfiring, the mufflers (cherry bomb glasspacks, which are painted bright red from the factory) have burned most of the paint off, and my right foot was HOT near the trans tunnel. The driver side muffler has a significant amount of paint NOT burned off, while passenger does. Is it possible the cats are clogged? One of the drivers behind me said whenever I got on the throttle tons of black smoke and crap was coming out. I got a mechanical black flag shortly afterwards for smoke and we packed up and went home. I also pumped out all of the fuel from the tank and put in fresh, but no change. The FR500 instructions for pumping out worked like a charm here http://www.fordracingparts.com/Mustang/fr500sownerinfo/Fuel_Pumpout_FR500S_v1.pdf. ½” hose fits very snugly over the fuel rail connector. Thanks, really trying to make it to the glen this weekend… Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 20, 2013 Share Posted September 20, 2013 cats ? why do you have cats on a race car ? loose those asap regardless if it's them or not... have you done a compression test ? Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 20, 2013 Author Share Posted September 20, 2013 i care a bit about the environment, so i keep the cats. The primary reason is that i read cutting the cats out does nothing for HP: http://kennebell.net/KBWebsite/Common/pdfs/MustangCatalyticConverters.pdf my compression tester didn't fit the sparkplug threads, a new one is coming in today.. Quote Link to comment Share on other sites More sharing options...
Grizlbits Posted September 20, 2013 Share Posted September 20, 2013 Are you absolutely sure the spark plugs are on the correct cylinders? Hot exhaust = retarded timing, maybe a cylinder firing at the wrong time. Bad plug wires in general? Quote Link to comment Share on other sites More sharing options...
stevepoe Posted September 20, 2013 Share Posted September 20, 2013 it's a coil on plug system. no spark plug wires per say......... I guess it's possible to plug the coil on plug wire into the wrong coils......they are a specific length so it would be hard to do but guess it's possible Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 20, 2013 Author Share Posted September 20, 2013 Are you absolutely sure the spark plugs are on the correct cylinders? Hot exhaust = retarded timing, maybe a cylinder firing at the wrong time. Bad plug wires in general? i was thinking the same thing, i stared and stared at the COP wires, but they are in the right COPs and don't reach their adjacent units. i could ohm them out from the computer pins.. Quote Link to comment Share on other sites More sharing options...
UBR Posted September 20, 2013 Share Posted September 20, 2013 Chris beat me to it, but that kind of heat and the back fires/missing is classic retarded timing. Check the wiring and also the crank trigger. Not sure if there are multiple mounting locations for the crank trigger, but we had a similar problem on one of our pushrod motors when the crank damper was marked wrong. j Quote Link to comment Share on other sites More sharing options...
olaaf Posted September 22, 2013 Author Share Posted September 22, 2013 Some news compression check is ~200 on all cylinders. The mufflers were plugged with cat material, but I think that was an effect not a cause. I got a replacement used x-pipe on the same day (because of all weekends to run out of gas on the welder…). Anyways, plugging into a borrowed much better scan tool from a fresh start I get 5 codes- P0358,P0353,P0354 P0357. These are all COP secondary’s, and P202 Injector 2. One of these has a brand new COP on it, all measured at 5.5kohm, and there is nothing wrong with inj 2. I think it’s the PCM, I must have cooked the output sections welding on the car for misc things after the cage was done. . amazing that the current decides to run though the computer grounds. Any tips for PCM swap, or just take it to the dealer because of PATS? Out for Watkins glen. Arg. mufflers cooked Quote Link to comment Share on other sites More sharing options...
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