hesitates under low throttle when moving from stop, and misses and bucks when cruising or trying to re-accelerate after coasting. Increasing RPMs w/ driving style (over 1500 RPMs) and disengaging OD at speeds over 45MPH helps.


I have been chasing this problem for a while. no fault codes except normal 111.

good fuel pressure
good vaccum
new EGR and most censors

I am wondering about ECT I have replaced the one on front of engine by water inlet. Is this the one that reports to ECU?

I have also heard torque converter especialy at 1500 RPMs

any help appreciated

 

the ect for your ecm is on the passenger side of the engine in the back. when has the truck been tuned up?

 

Its been a year. cap and rotor about 3 yrs. Checked #1 plug and it looked good very few miles over the last years.

Im going to try to find the ect, truck seems to run a little better when cold.

other than that I was leaning toward injectors but they are $45 ea, and I dont know thats the problem

 

I would try some fuel injector cleaner in the gas tank. Use a name brand fuel injector cleaner and follow the directions on the container. That's about how my '88 f-150 with the same engine was acting and fuel injector cleaner straightened it right out. I know a lot of people will try and tell you fuel injector cleaner is snake oil, my reply to that is: then they must get it from magic snakes.

 

I use fuel cleaner regularly B-12 or sea foam, I have thought about getting some ggod stuf from the dealer but have'nt seen any difference with these.

Could still be injectors truck has a lot of short trips to ball practices and day care over the last several years.

it seemed to run better this morning when cold untill it started to warm up and was still not as bad as it has been in warmer weather.

 

I am going to replace both temp censors this weekend and maybe the torque converter and see what happens. I hate to throw money at it. So maybe just the censors.

 

Why don't you start the truck & run the KOER scan while the engine is below operating temp. to see if it coughs up a #21 error code like it should when the ECT sensor is scanned before operating temp is reached. It should show up on the KOEO also. It runs better until it reaches Op. Temp.(195F) which is when the PCM takes over. Prior to that during warm up cycle the air/fuel ratio is purposely in an over rich state but is influenced by the IAT(Incoming Air Temp.) sensor which screws in around the same area as the ECT Sensor on my 5L. Having effect prior to & during PCM Function,you probably want to replace that too. The Coolant Temp. Sender for Gauge readout is screwed in closer to the Thermostat housing an is the only one w/ a single wire connector & no influence on the PCM. The over rich state during warm up can hide a multitude of sensor inaccuracy & component function sins but there effects become more dramatic after the ECT informs the PCM that 195F has been reached and it's time to make itself useful (or a real pain in the ***). This is where driveablility & controlled emissions efficiency can have a parting of their ways and drive ability occurs in spite of the PCM more than because of it. Once the PCM goes into closed loop function, whatever is or insn't happening, is or isn't going to happen with a 14.7:1 air to fuel ratio which leans out to promote efficiency and protect the converter at the cost of performance. Anyway, you would think that whatever would make the truck run so badly, would show up in the scans and make you wonder if the results can be trusted as Representative of whats really going on. Well guess what component on your truck has the lowest failure rate regardless of year, model or engine? Yep! but even so, I'de probably run a couple of scans, disconnecting different sensors and valves each time, purposely generating false codes to make the 111's easier to swallow as an acceptable premise to start with. Then just concentrate on what might cause those symptoms w/o resulting in error codes. Like multiple sensor readings although inaccurate, still within range. Excessive resistance of plug wires, hairline crack or worn cap & rotor, fracture in spark plug insulator, rapid pressure bleed down rate at the fuel rail by injectors after fuel pump shuts off, fuel regulator malfunction airflow restriction to air intake, Initial timing set less than stock 10 BTDC , O2's mileage overdue for replacement resulting in slower Signal switch rate and/or O2 sensor probe pick up contaminated by deposit buildup from over rich conditions like incomplete Cylinder ignitions & misfires resulting in decreased sensor accuracy (even pulling the o2 sensors and douching out through the probe port openings W/ Electronic contact Cleaner has always proved benifitial for me. Then there's always poor path to ground for the fuel injectors & everybody's Fav: Cylinder compression test including rate of pressure bleed down. Also, I read at Alldata that injector function can be affected by battery w/ a bellow normal charge state &/or erratic alternator output.

 

IF your going to drain the tranny fluid , you should put in a can of "TransTune" & drive around w/it a couple of days before draining. Great stuff! Same Co. that makes SeaFoam!

 

great info thanks
I have replaced the IAT and I'm pretty sure the ect. they were from auto zone so maybe still inaccurate. The truck has been running bad at start up and at temp, except a few cold mornings it ran good untill warmed up.
I had many codes when I started tying to fix this problem starting with EGR out of range. I was getting the ect trouble durring KOER untill I realised It had to be warmed up.
According to my Haynes manual most of my sencors were out of range so I replaced them only to find that the new ones were off too, so either my book is wrong, my meter is wrong, or auto zone sencors are junk.

now the injector info may help

 

The other day the truck would not start, fuel pump ran engine lights on no starter. I wiggled the shift lever and it cranked. I have not looked into this problem yet but I guess it is the MLPS or nuetral safety switch.

Can an MLPS cause the truck to run bad.
I have also been considering torque converter chatter, but I don't think that could cause hesitation off the line.

 

How would I check for a good ground at the injectors, On negative wire?

Fuel pressure is fine it holds steady w/ truck off and running

I have not checked timing or compresion