Old thread was getting a little long, so I started a new one, anyways here is the current problem being troubleshooted, Hard starting (long cranking before engine fires), problem seems to be getting worse. Bronco 5.0 302 EFI, E4OD
Here is some raw data from the ECM, this data set was taken after vehicle was driven, shut off and sat for 20-30mins. I will take another set when it is cold in the morning). I also code scanned the truck again and found a continuious key on engine off code "334 EGR(EVP) Voltage above closed limit", don't know what set this off, but since I cleared it, it has not returned. key on engine running generates 111 (no codes present), and now key on engine off generates 111 (no codes present)

Engine Off Data
RPM 0
O2S1(mv) 2
TP=TPS(V)1.16
MAF=MASS AIR(V) 0.00
TP MODE C/T
BP=BARO(kpa) 102
CCC=TCC OFF
ECT(V) 0.53
ECT(DegC) 98
IAT=ACT(V) 2.21
IAT=ACT(degC) 40
IAC=IDLE AIR(%) 0.0
VEH SPEED(MPH) 0
EPC(PSI) 8.0
STE=EVP(V) 0.46
EVR(%) 0.0
INJ PW1(ms) 0.00
OPEN/CLSD LOOP = OPEN
SFTRIM 1(%) 0
LFTRIM 1(%) -6
SPARK ADV (deg) 0
VPWR=BATT (V) 11.9
VREF(V) 5.01
MAN LEV POS = PARK
MAN LEV POS (V) = 4.41
TR=GEAR PRND
BOO=BRAKE SW = OFF
TFT=TOT(V) = 0.97
CANP=PURGE OFF
PARK/NEU POS PN
ACCS=A/C OFF
OCTANE ADJ = OFF

Someone here mentioned to look at the ECT sensor, welp it is reading about 90degC, I'll check it again when engine is cold, but just for the fun of it I unplugged it (infinate resistance = lowest possible temp). ECT Instantly went down to 35-37DegC, attempted to start, and I was quite surprised to see it just cranked, and would not fire at all, cranked for almost 15 seconds, no start. Plugged it back in and the engine started, also code scanned and as I suspected, the computer caught me, ECT high resistance code was generated, cleared it, and now I'm stuck, I guess I could put a 100k pot in place of the ECT sensor, and dial in ambient temp, but I could also wait until engine cools down as well, and see if the sensor reads ambient temp. I feel like every road I go down with this problem leads to a dead end (like the ignition system which I originally suspected). If anyone needs more info or test results, let me know what you need (ie temps, pressures, resistances, voltages, ecm data, etc), and I will get it to the best of my ability. Is there any way to definitively narrow this down??? Injector Pulse width maybe?
Thanks
Brian

 

Also I just thought of something else noone has mentioned yet. How about a clogged catalytic converter, would that cause these symptoms?
Brian

 

check your tps, i think it is out of range. Usually they use .5 at closed throttle. Not sure if is causing the problem hope it helps.

 

clogged cat would cause power loss at rpms above idle. wife had a monte carlo with a clogged cat, car would sputter above 3000 rpms and had no power. it had even blown the intake gasket before we found the problem. Is the engine running hot at all or any loss of coolant?

 

TPS is out of range. Closed throttle TPS voltage spec is 0.8vdc minimum, 1.0 vdc max.

 

TPS high could be caused by the fact I raised the idle speed when I installed a 200A high output alternator 3-4 yrs ago, it needs higher rpms to put out at idle than a stock unit. 1.16 is not too far out of line, not enough to cause hard start, when stepping on gas with engine off, TPS voltage varies quite smoothly. I think its time to look elsewhere. Also as far as a cat problem is concerned, it seems to be consuming coolant, but on an engine with 155k miles, that is not out of line either, as stated in previous post, there has been a loss of top end power (mainly at very high speeds), definately not sputtering or running rough, just power isnt there. Definately not overheating, coolant gauge stays in middle, and ECT shows about 91degC on road.
thanks
brian

 

For what it's worth I installed new bosch platnum plug in my 96 351 bronco and from the very first start it had problems starting when cold, also lost some gas mileage. I was told that those plugs would not work good with american trucks due to high current needs, so I installed some champion truck plugs and haven't had an issue. I suspect unless you have recently switched plugs you have some other problem.