troubles..half throtle or more

[blbt1128]

ok well i just bought 1128 up in philly, and well it hasnt ran right since i got it. it seems to run just fine under half throttle, but getting into it sometimes it will do a straight cut out even at low boost or backfire through intake. plugs have only been in there for 900 miles and look like chicken shit on em, but there stock heat, usual experience tells me there to cold, but ppl on here say diff. mods and things done so far are as follows
-supposedly has eagle rods or some sort and forged dished pistons unknown brand or cr
-walbro pump and afpr set at 40 w vac unlugged
-new cap, rotor
- aftermarket cat, flowmasters
- dummy i bought it from didnt think an air filter was necessary so i still havent got one on it
-no codes at this point but it did have a 42 and something w 02 sensor but it was due to dummy puttin the wideband in the original hole and original in behind it screwin the reading. ill wire the wideband in soon though.
well hope u all have some ideas, is it possible havin no filter is the reason the shits on the plugs?

 

[Jimmy]

Re: troubles..half throtle or more

There has got to be some local guy with Datamaster near you that can help..Having some logs of it running would be nice..

Backfiring through the intake sounds scary.Stop driving it NOW before it implodes.


So what do you know aboot the truck? Do you have a real boost gauge? Fuel pressure gauge? What plugs at what gap? What octane gas you running? What injectors? What chip? Timing set right? Firing order correct? Vacuum leaks?


BTW a Flow Master is a chambered muffler and is inappropriate for turbo applications.

Post as much as you can,cause it's really a crapsoot at this point.

 

[blbt1128]

Re: troubles..half throtle or more

well its got the plx gauges for boost, vac, afr. i turned the wastegate down to make sure the cutting out wasnt overboost, so it hits 10 max and cuts. bosch 30, press gauge on rail. .030 gap. everything seems right. pulls like 20 pounds of vacuum at idle. the chip....well thats one thing i have no idea. i wish i could get a stock burn because i kno whatevers in there isnt original, looks like the base for it has been changed or somethin. and the prom is aftermarket. but idk. regardless i have taken 2 trips to ny without skippin a beat, put it down half throttle on the highway and it pulls pretty hard. can beat tons of cars from like 70 to 90 and it seems strong off the line until 2nd when it really starts actin

 

[SY2455]

Re: troubles..half throtle or more

You really need to get a Datamaster run on it without knowing what kind of chip you have. My truck does not like anything under 45 lb fuel pressure. It will run, but doesn't like it, I only turn it down for the trip to get it smogged. The stuff on the plugged is not good at all, Look at #4 and 5 in the link below. Do your look like these?

http://www.ngksparkplugs.com/techinfo/spark_plugs/faq/faqread2.asp

Get rid of the flowmasters muffler, These truck don't run good with them and it could be part of your problem. Do a search on here and you will find more then enough about them. How much gas you have in the tank will affect how it runs too. How old are the spark plug wires? It may look like a freeway interchange at night under the hood.

 

[blbt1128]

Re: troubles..half throtle or more

ok things i did today, was jerry rig a fliter cone filter on, then since imin the navy we have an auto shop,roll it in there put it on the lift excited that the cats prolly plugged, lopped it off and, heartbreaker its already been gutted. so i figure maybe it broke up and plugged the mufflers so i took it around the block w just the downpipe, nope still runs like a pile, backfirin through intake. so irritating!! so had to weld the shit back on and now got some leakies.

 

[blbt1128]

Re: troubles..half throtle or more

changed wires today, no avail. and correction,now that the exhaust has leaks those backfires arent intake like i thought, exhaust

 

[saudisy69]

Re: troubles..half throtle or more

Had this happen to me once in my hi mile sy, it was a clogged fuel filter. To check for this I taped my fuel pressure gage to the windshield and went for a ride, when I got into boost fuel pressure would drop off.

 

[blbt1128]

Re: troubles..half throtle or more

ok well driving it around and closely monitoring what happens, at 3200 rpm is when it starts having problems regardless of what boost is at because i have adjusted the wastegate a few times.it does backfire through the intake, and then all of a sudden a shotgun blast out the exhaust. now im really confused i was thinkin lean for a min. ok so lets talk mods. should i go ahead drop a small cam in it, a known burn, bigger turbo etc? new ecm maybe. i mean seriously wherever the problem is somethin will find it,its not really solving the problem at hand, but its eliminating alot of factors, i checked vacum lines, sprayed ether around the intake, and it looks to have nothing wrong there. curiously the one intake tube at the front right behind the thermostat keeps blowing off causing major backfire. it has an msd coil, doubt any problem there. could timing have moved? i have a fluidampr hopefully the right size, this is so irritating, i have never had somethin that i couldnt figure out what was goin on, then again i usually just dropped a smallblock in everything. another thing, a sy for a dd isnt the thing to do. it sucks, asshole tailgatin and ur thinkin boy if this gets hit who knows where im gonna get parts lol.

 

[SY2455]

Re: troubles..half throtle or more

Have you done a compression test or leak down test on the engine. Have you verify timing and check the harmonic balancer to find out if it slipped?

http://www.syty.net/forums/showthread.php?t=65979&highlight=harmonic+balancer

You may have a valve that is not right and acting up in the higher rpm range or a flat cam lobe. All of your vacuum lines should have tie-wraps or clamps on them to keep them from coming off. Do you know what all has been done to the engine other then what you post in the 1st posting? Did you get all the paper work?

 

[berzerker]

Re: troubles..half throtle or more

m engine started doing them same thing .. right before an headgasket let go ! do a compression test .

 

[blbt1128]

Re: troubles..half throtle or more

k well today i checked fp again and it wasdown from the 40 i had it at to 32, i went to crank it up to 50 and it took 4 complete turns of the reg to get there, after that i went for a spin and was so happy that i could stomp on it and it wouldnt backfire or carry on at all, then all of a sudden it started doing it again only at more throttle opening. is the pump taking a shit? last 2 days i havent been able to go more than 1/4 throttle without fallin on its face, backfirin. supposedly its a walbro in there, but i bet its a pile off ebay.

 

[SY2455]

Re: troubles..half throtle or more

k well today i checked fp again and it wasdown from the 40 i had it at to 32, i went to crank it up to 50 and it took 4 complete turns of the reg to get there, after that i went for a spin and was so happy that i could stomp on it and it wouldnt backfire or carry on at all, then all of a sudden it started doing it again only at more throttle opening. is the pump taking a shit? last 2 days i havent been able to go more than 1/4 throttle without fallin on its face, backfirin. supposedly its a walbro in there, but i bet its a pile off ebay.

Sounds like your fuel pump or AFPR is going bad based on what you said here. I would change out the fuel filter and cut it open to inspect it .

 

[AutoVation]

Re: troubles..half throtle or more

Is your distributor ok? When I changed my cap/rotor the first time I ended up cracking my distributor magnet and it had problems beginning at the same RPM no matter what throttle level I was giving it.