One last shot... Breaking up!

[BoostedSUV]

Re: One last shot... Breaking up!

did you try injector swap, i have brend new 60's but seeing the same issue, brand new engine, etc. under cruise it will run around 15afr and slwoly creep up to 18 afr's then miss. Im going to take a look at my csv log from tunerpro and see what different rpms and paramters it goes lean at. my inj duty cycle was high also from what I remember. It seems to me its a intermittant problem for me, it comes and goes randomly. im running and brand new wideband also.....

Injector swap is about the only thing I haven't done. I did find a few sets that members are willing to let me borrow. I just need get the ambition. I too have a brand new wideband, I put it in to help troubleshoot. I'm sitting in between 14.5 and 15.5 driving around but once I get close to 2500 the numbers start to climb to 19+ and I get a bad miss. Mine is very RPM specific and does it every time.

 

[nallj92]

Re: One last shot... Breaking up!

ok just reviewed my files, my miss spot is at 2000 rpm. injector pulse width is normal.- i was wrong. average map reading at this miss is around 60kpa give or take. but for the whole file, the 60kpa area gives normal afr's for the most part

 

[BoostedSUV]

Re: One last shot... Breaking up!

Anyone think I could have an injector that's hung open a little? #6 plug was much richer than the others, when I add fuel pressure then trucks gets worse, when I take away pressure it gets better..

Is it possible the increased fuel pressure fattens up one cylinder and throws off the O2 reading therfore causing though truck to lean out and get a lean miss? Doesn't appear that way in DM files though, it seems to be lean from the get go and the ECU tries to add fuel but the miss/lean condition continues.

when I reduce fuel pressure truck shows rich from the get go and tries to pull fuel.. totally opposite of what i would think would happen.

I don't know.. I'm reaching out here because I'm lost and don't kow where else to turn other than a parted out TY in parts for sale section...

 

[WyoSyclone]

Re: One last shot... Breaking up!

ok I did a few DM files and went over them with Nolan and he sees what i see... The more fuel I add (base pressure turned up) the leaner the truck shows and the more fuel the PCM tries to add, the less fuel I add (dropping the base FP) the richer the truck shows and the PCM tries to pull fuel... does that make any sense??? Completely opposite of what's supposed to happen! I tried it with FP base at 50, 40, and 30. The lower I go the better the truck runs but that's not the fix. I've got something really wacky going on!

If you add more fuel pressure, the injectors are trying to open against a higher pressure. I would check voltage/amperage supply to the injectors, and check all grounds. Also, if I'm thinking right after a glass of wine... if you turn the pressure up, and the pump has a problem, you're going to aggravate the problem with the pump. It may be able to hold 50 lbs static, but once you open the injectors the pump can't push enough volume to keep it from going lean.... I really think you're looking at a pump/inner tank line issue if you've got good voltage at the ECM and your grounds are good.

 

[SloGN]

Re: One last shot... Breaking up!

I'm days away away from pulling the plug on my Sy/Ty ownership! I've been fighting an unknown issue for 4 weeks now and I've checked everything under the sun and can not resolve it! Please give me some more ideas or TY 2031 will be parted out. That's not a threat to anyone, I've just had enough...


I posted on this in another thread and it lost action, and I've tried more things so lets start over. My truck is not even driveable right now... it ran absolutely amazing up until one morning when I drove it work and it barely made it in with out any warning. Truck stumbles and breaks up at 1100, 1900, and 2500. It just goes lean and I can hear it popping through the exhaust. All started after I installed an Autometer elec FP gauge and took out Air/Fuel gauge. (Could be total coincidence??) Didn't drive the truck 4 days after I installed the gauge, but it ran perfect when I parked it the day I did the install. I've done a lot so there's going to be a lot of info to try and save some suggestions so bear with me.

I changed ECU to a reman spare I have, I swapped out coils, changed cap and rotor (MSD dist is only a year old), verified timing with EST wire unplugged, Ohm tested plug wires (all between .09 and ,13), sprayed wires with water to check for short, tested ALT voltage (13.8v), Checked all the wires I ran through the firewall to be sure I did not slice any when feeding wires though, Changed eproms in my Moates Adapter, tried stock memcal, tested TPS, reset IAC, installed Wideband to verify O2 lean reading (O2 dropping in 80's, WB reading 18 +), More fuel pressure causes it to get worse (base 50lbs I verified with mech and elec gauge) 38lbs at idle, Vac is 15hg at idle/18 when truck stumbes (in nuetral), Checked for vacuum leaks (has a new vac hose kit I put in during group purchase), I sent DataMaster files to Nolan and he doesn't have a clue either, Datamaster shows the truck going dead lean when its breaking up... O2 counts in the 80's and s-term counts jump to +42 until it hits 2500rpm!!! Everything else appears to be normal! (i will gladly email them to anyone),...

one thing I didn't change was spark plugs but they are only 10 mos old (NGK iradium .025 gap) Don't really see why they suddenly would have gone bad?


I'm sure I will think of more things I've tried and I will add them in as I recall. Please help me out, I love this truck and my next thing was to do a body swap and save a rusted TY but the way it sits it will be parted if I can't resolve this. TIA!

you need to pull those plugs and junk them. I had a issue with those in my gn . They got to where it would not fire thru the boost. i changed out the wires and ignition coils and come to find out those plugs were junk. i installed a set of autolite #23's gapped at 28* and bam fired rite thru 25lbs of boost.


one thing to remember that when you have a sylinder miss fire the raw unburnt fuel gets blown into the exhaust to where it gets lit by the next cylinders firing. when this occurs it burns up the oxygen in the exhaust thus depleting the oxygen. so the o2 sensor reads lean due to the lack of oxygen.


when that happens it drives the stock ecm crazy and then the ecm tries to richen the mixture more adding to more issues.

Trust me on those plugs being junk! it drove me bat shit too for weeks then for shits a giggles i changed them out problem solved.

 

[BoostedSUV]

Re: One last shot... Breaking up!

you need to pull those plugs and junk them. I had a issue with those in my gn . They got to where it would not fire thru the boost. i changed out the wires and ignition coils and come to find out those plugs were junk. i installed a set of autolite #23's gapped at 28* and bam fired rite thru 25lbs of boost.


one thing to remember that when you have a sylinder miss fire the raw unburnt fuel gets blown into the exhaust to where it gets lit by the next cylinders firing. when this occurs it burns up the oxygen in the exhaust thus depleting the oxygen. so the o2 sensor reads lean due to the lack of oxygen.


when that happens it drives the stock ecm crazy and then the ecm tries to richen the mixture more adding to more issues.

Trust me on those plugs being junk! it drove me bat shit too for weeks then for shits a giggles i changed them out problem solved.

I took out the NGK iradium plugs that were flawless up until this point and I put in a brand new set of NGK TR55 plugs in and that didn't solve my problem either. I was almost convinced I was having and ignition misfire but I have changed the entire ignition system at this point... plugs, wires, cap, rotor, ign module, magnetic pick-up and the ECU.. what's left?

NGK are the plug of choice around here, I had autolite 103's in my truck for a while and they were junk. I've good luck with NGK's so far

 

[leadfoot]

Re: One last shot... Breaking up!

How many miles on this engine?

Tan timing wire reconnected?

Check coil when hot (once had a bad coil which would break the field due to hairline crack)

Correct vacuum line going to FPR? (since it is doing opposite) Did you re install the check valves the right way?

When was the last time the fuel filter was changed?

Start truck in pitch black, open hood and have some one rev engine to 2500+ RPM look for arcing.

Use DVOM (digital volt ohm meter) to check wire continuity from ECM to sensors (starting with O2)

Check TPS with DVOM -should be smooth resistance. If it jumps it may be bad.

Any distributor shaft play? (lateral) -distributor gear worn.

Hang in there.

 

[Icarus-54]

Re: One last shot... Breaking up!

I've read this entire post and the only thing you havent tried is spraying tuner cleaner on your ecm conectors.They could still be tight and not working right due to some minor oxidation.Had a similar problem,truck would get some extremely lean spots under acceleration then eventually would intermitingly not start.Went to Radio Shit and bought a can of spray tuner cleaner (for tvs) and problem solved.Just a thought.
Jack

 

[BoostedSUV]

Re: One last shot... Breaking up!

I've read this entire post and the only thing you havent tried is spraying tuner cleaner on your ecm conectors.They could still be tight and not working right due to some minor oxidation.Had a similar problem,truck would get some extremely lean spots under acceleration then eventually would intermitingly not start.Went to Radio Shit and bought a can of spray tuner cleaner (for tvs) and problem solved.Just a thought.
Jack

Huh... That's an interesting thought Jack. I will stop at Radio Crap on the way home and pick some up and give it a shot. What could it hurt? I may even spray it on all the connections at each sensor. Youte describing what I have going on so its worth a shot. Thanks for taking the time to read this thread and offer your insight!

 

[ViciousV6]

Re: One last shot... Breaking up!

When i was running my Vortec Heads, I was using TR6 or Stock # 4177 plugs not TR55


Gapped @ .030 to .028 is all the gapp tyou need

Advance Auto usually stock them by me.

You can call me if you wanna run over it play by play. I'm getting reay for the 3rd Truck to be fixed that came down from NY because of similar issues and its mostly stupid little things that happen.

Ralph
ViciousV6

 

[sly dvl]

Re: One last shot... Breaking up!

One thing I noticed, with base fp set to 50 the truck will idle at 42psi with 15hg in vacuum (on the gauge). Shouldn't it idle at 35 with 15hg in vac? isn't it 1 for 1 for boost and vac?

No. 2" of vacuum is equal to the loss of 1lb of pressure. So, 15"hg is equal to the loss of 7.5 lbs. 50lbs - 7.5lbs = 42.5 lbs. Right on the money.
Boost is obviously pound for pound.

Now, I'm not exactly sure how a WB O2 reads, but I know that with a stock O2, a misfire of any kind will result in a lean reading, REGARDLESS OF THE CAUSE! A stock O2 is looking at oxygen levels in your exhaust. If you have a mis, the oxygen that went into the cylinder never burns and comes out again. The O2 see the excessive oxygen in the exhaust and the ECM richens the mixture to try and compensate.

So, what I'm saying is are we sure it's going lean and causing the mis, as opposed to going rich, blowing out the spark and giving a false lean reading?

 

[Windedv6]

Re: One last shot... Breaking up!

Check the fuel return line for blockage. Possibly kinked somewhere. If blocked and cannot return fuel correctly to the tank you wiil get a rise in fuel pressure enough to mess with the computer. It could act only at certain times as amount of fuel needed to return to the tank varies with different fuel needs vs pump pressures.

Check for a kinks in the hard line behind the upper engine and bellhousing area. Also check the areas where there is rubber hoses. If needed unhook the line below the regulator and put air through it to make sure it is fully open all the way to the tank.

John

 

[autoaddictions]

Re: One last shot... Breaking up!

FUEL PUMP??? It gets hot it gets worse!!

 

[BoostedSUV]

Re: One last shot... Breaking up!

How many miles on this engine?

Tan timing wire reconnected?

Check coil when hot (once had a bad coil which would break the field due to hairline crack)

Correct vacuum line going to FPR? (since it is doing opposite) Did you re install the check valves the right way?

When was the last time the fuel filter was changed?

Start truck in pitch black, open hood and have some one rev engine to 2500+ RPM look for arcing.

Use DVOM (digital volt ohm meter) to check wire continuity from ECM to sensors (starting with O2)

Check TPS with DVOM -should be smooth resistance. If it jumps it may be bad.

Any distributor shaft play? (lateral) -distributor gear worn.

Hang in there.

15k on motor

tan wire is connected

I changed coils

I replaced wires

I continuity tested each wire starting from the ECU to eac sensor

Distributor is 6 months old

TPS voltage is good and I even changed a spare...

Fuel filter is 1 year old

 

[BoostedSUV]

Re: One last shot... Breaking up!

When i was running my Vortec Heads, I was using TR6 or Stock # 4177 plugs not TR55


Gapped @ .030 to .028 is all the gapp tyou need

Advance Auto usually stock them by me.

You can call me if you wanna run over it play by play. I'm getting reay for the 3rd Truck to be fixed that came down from NY because of similar issues and its mostly stupid little things that happen.

Ralph
ViciousV6

Hey Ralph! I had the NGK TR7ix plugs in the truck prior to having any issues, they were in the truck for 10 months .. I just threw in the TR55 because they were cheap, Awful Zone carried them, and it was an easy way eliminate plugs.. The ones that came out were gapped at .025, the new ones are gapped at .028. I think ign. misfire is my issue but plugs are out as well as wires, cap, rotor, coil, ECM, ign module, and coil pick up

 

[BoostedSUV]

Re: One last shot... Breaking up!

FUEL PUMP??? It gets hot it gets worse!!

Fuel pressure acts normal... I have a gauge inside the truck. At 18 psi at WOT the FP is perfect and the truck doesn't skip a beat. I find Fuel Pump or Fuel volume being the problem hard to believe. I think I'm getting a very RPM specific ign missfire.

 

[BoostedSUV]

Re: One last shot... Breaking up!

So, what I'm saying is are we sure it's going lean and causing the mis, as opposed to going rich, blowing out the spark and giving a false lean reading?

I'm with you on this one Kevin but I can't figure why, and why so RPM specific.... O2 and Wideband both show lean at the point I'm getting the "miss"

 

[nallj92]

Re: One last shot... Breaking up!

as much as i hate to say it, i would try to swap distributors just for a sanity check

 

[BoostedSUV]

Re: One last shot... Breaking up!

as much as i hate to say it, i would try to swap distributors just for a sanity check

The distributor is a fairly new MSD plug and play unit. I did change the ign module and magnetic pick up, cap/rotor... What else could go wrong in a distributor? I replaced all the vital "organs"

 

[Luke]

Re: One last shot... Breaking up!

you can have plenty of fuel pressure but not enough volume, ive been bitten by this a few times on customer cars