cypris09

iTrader: (1)

Hey guys I'm trying to button up my 5.3 swap in my 87 trans am. Finally got a tune from Texas speed. Car fired right up and ran pretty good for 10 or 15 min. It stalled out and wouldn't start. So I tried the next day and it started then died. Now it won't start again. New set of plugs and go figure it has the same problem!
Going to do a compression check to make sure that's good but could definitely use some help on this guys. I'll get some more info down once I get home

cypris09

iTrader: (1)

Im running a comp cams 54-428-11
ls1 intake and racing innovations long tube headers. Also have the truck MAF and motor is from a 01 gmc sierra

bczee

iTrader: (12)

Is it throwing any codes ? Fuel pressure correct ? All cyc firing ? Could be many contributing areas of problems.

Get a scanner on it and monitor the fuel trim and O2 readings.

Good luck and keep us posted on what your finding or was the fix.

cypris09

iTrader: (1)

Hopefully ill be getting a scanner soon to get some live data. Had a buddy come over and it definitely looks like its fouling because of to much fuel. No codes and the o2s are new not that that means anything. Texas speed tuned it, basically said check o2 and MAF and fuel pressure. So basically if i can get a nice scanner with some live feed ill look at fuel trims and o2 sensors. Ill buy a thing of carb cleaner too to confirm no vacuum leaks.

cypris09

iTrader: (1)

So I got the compression test done. I'm only at 90 psi in all 8 cylinders. Seems weird to me. Someone had mentioned that since it was so Rich that maybe I washed the cylinders and to put oil in and do it again. This motor was fine before I installed it. All I did was swap a oil pan, cam and sent the heads to get checked/cleaned. Not sure what else to do here. Anyone else?

RicOtt

90 is low, but it should run. I doubt you washed the cylinders out that quick. When you checked compression, were all plugs out at the same time? If so crank it over and take the reading on the 4th compression stroke (per GM service). If you are still getting those numbers,squirt a little oil in each cylinder and then take the reading, if your number comes up, usually a sign of weak rings. If it doesn't come up, perform a leak down test (if you can get the tool). If not that, pull the valve cover and check the rockers to make sure the valves a closing all the way (pushrods may be long for cam).

Finally, you fuel pressure is not being regulated by a vacuum regulator that uses intake manifold vacuum, is it? If it is, check the line to verify the diaphragm has not split. If it has, gas is drawn into the manifold, which will foul the plugs very quickly. I have had this problem on two engines (a truck motor manifold LS engine and a camaro 3800 engine. I'm told the ethanol is the cause. Good Luck.

66Chevellelq4

Compression could also be low if the cam was installed retarded or advanced. Sometimes dot to dot isn't actually dead on depending who makes your cam. Maybe try degreeing the cam as well? Hopefully you get it figured out!

cypris09

iTrader: (1)

Well that's a possibility I thought of.Turns out I think I did Wash the cylinders. Squirted in a little bit of oil and tested it. Went from 88 psi to 150 so I think as long as I get that in the rest that solves on problem. My question is was this a result of my first junk tune or after my new tune from Texas speed and I have something else wrong?
I'm using a vetted filter/regulator. Checked the fuel pressure and I'm at 58 psi.
Hopefully I'll get a scanner on this before I get it started and get some readouts and this is the problem.

cypris09

iTrader: (1)

Little update, The scanner i could get my hands on supposedly cant scan modified cars? (or at least thats what i was told). It could only read engine codes and i had none. Put some oil in cylinders all 8 went to 160 psi and is still currently holding.

Sent ecm to texas speed again to go through it. I assumed when i told him i had a ls1 intake he would tune for ls1 injectors and that would be false. New tune and cleaned plugs it starts but really doesnt want to idle. A little bit of play with the throttle and it finds a way to idle. Plugs get some carbon build up but no gas smell. So thats a plus!.
Im thinking i need to clean my MAF just because and maybe get new o2 sensors. Without having a real scanner though im really just guessing.

With the clean plugs it idles amazing(after you play with the throttle) Great throttle response.

Is there a way to clean o2 sensors if it just a bunch of carbon build up? Id hate to throw in 60$ for new o2 sensors for that not to help. Kinda the same idea with the plugs. really trying to avoid just tossing money at the thing. : /

cypris09

iTrader: (1)

Another update. Started it up (played with throttle till I got it to idle) I was told to unplug map sensor, so I did. Idles better you can Rev it and it won't fall on its face.
Roughly an hr later I went out to start it and it fires right up now no need to help it idle or anything.

No real idle time or anything like this. I'm not sure if it could cause problems running it to long with it unplugged. What do you guys think? Sound like a bad map?

cypris09

iTrader: (1)

Well i finally got hptuners and did a datalog. If anyone is curious or can help me figure this out, you can find the Log via

http://www.hptuners.com/forum/showth...ng-really-Rich

I think im leaning towards a vacuum leak but im not sure. So hopefully someone with some real knowledge of these motors and some tuning please help me figure this out!