codes 171 and 174

[towiseman]

I have P-0171 and P0174 on my 2001 E150. Changed MAF, checked and cleaned EGR, changed DPFE, checked for vacuum leak with smoke and still the service engine with codes 171 and 174 comes on. What else to look for??????
Please help. I will need to get smog check soon. Thanks
towiseman@yahoo.com

[autojoe]

do you have a good scan tool?able to monitor short and longterm fuel trims?koer test?usually caused by vacuum leaks.....low fuel pressure....dirty maf.....

[towiseman]

Thanks for reply. The MAF is changed to new. Checked vac with smoke and no leak. Frame freeze date for 2 occasions are as follows;
A / B
Abs. Tps =20 / 20
Eng. Spd=1033 / 1291
Maf=0 / 0
Cal load=44.7 / 69.4
coolant=190 / 189
Iat=3.1 / 5.5
Ign Ad= -3.9 / 7
ST frame 1=5.5 / 8.6
Lt frame 1=8.6 / 14.1
veh spd=0 / 0 (always I get the same on 0 speed)
Let me know please
Thanks Abe

[autojoe]

what are your stft and ltft at idle/1500/2500/3500 rpms?if high at idle and get better at higher rpms than vacuum leak.if good at idle and get worse under higher rpms than possible dirty maf or low fuel pressure.maf should be able to put out over 4 volts under a snap throttle....but need a meter with fast enough capture capabilities min/max glitch capture or a labscope.have you looked at 02 readings at idle.....towards low end?have you checked fuel pressure at idle and also snap throttle?may be a weak pump.do you have a fuel pressure gauge?if you have a scan tool that can do a ford koer or key on engine running test and fails for 02 lean condition and suspect a vacuum leak.should have shown up in a smoke test.what size engine/model and year?any tsbs on this problem?what type of scan tool do you have?dirty injectors/fuel filter?

[towiseman]

Thanks for reply. Injectors were cleaned by my mechanic with using Seafoam straight to engine with special tool. engine is 4.2 L, 6 cylinder, 2001 E150. Fuel filter has been changed. used seafoam in intake (through vacuum line). cleaned throtle.When engine is completely warmed after a while of driving, it runs like a clock. never had any issue such as sudden change, hesitation, etc. also, when first start in morning it is perfect. but when temperature reaches close to normal driving and if I stop and my foot on brake for a few minutes the engine will make a gesture like it is going to stop but it makes it up and rpm goes higher again. I also hear a rattling noise like a razor blade shaking when my foot goes on brake (only before the temperature reaches normal)
I appreciate for the info you provided. However, I do not have the Low/High numbers to compare those you asked for. Such as fuel pressure, low O2, stft, ltft at idle, 1500,2500 ...and other numbers that I need to compare. Please write the normal range of them for me or tell me where to find them. I looked in internet but did not find. also, what is tsbs? "snap throtle" means full open? I do not have Ford koer . Please give me the good range numbers. Thanks

[autojoe]

if only happens when brake applied....check brake booster hose and connection.your probably going to have to take to a shop that specializes in diagnostics.these codes will only set when fuel trims go above 25%.need a good scan tool to monitor short and long term fuel trim under various load conditions....that is just a start.why did mechanic clean injectors?did he do a injector drop test?shop did injector cleaning/smoke test?what did they say about diagnostic scan data info?

[irenearris1]

It checks good.

[towiseman]

Hi
I asked mechanic to clean injectors and we did smoke test to see if there is vac leak. there was not. He could not tell why the code is still there.
taking it to dealer will cost me more than the van value!
Will you post the normal values for fuel pressure and other tests that you mentioned in previous email.

[autojoe]

fuel pressure 35-55 psi.....low end at idle and snap throttle upper end.fuel trims should be within plus or minus 10%.(-)minus below zero computer subtracting fuel for a rich condition....above zero lean condition computer adding fuel for a lean condition.you want to check fuel trims at different rpm.

[tempfixit]

Do you havee ay exhaust leaks before the 02 sensors?

[towiseman]

Hi
My 2001 e150 is going to be stored for a couple of weeks. which fuse to pull out to reduce battery discharge until I run it again?