crook

OK I HAVE A 350 PRE 87 BLOCK 305 HEADS PORTED POLISHED with thicker head gaskets and bigger valves tpi siamiesed runners and plenum and intake modified airfoil chip for 30 lb injectors and 30 lb injectors double roller timing chain ,stock 5.7 roller cam ,retro fit roller lifters, 1.6 ratio roller rockers, afpr, speed density tpi and paxton supercharger. i finally got the car put back together and was running fine all the way home from my shop and idled smooth ,till the next day started running like crap found one dead injector ,from one day to the next that was wierd so i put in the 30 lb injectors and the chip as i was running factory 5.0 chip with 5.7 injectors before , and i have the same problem with either combination i changed back and forth 3 times , its not supercharger related as it does the same thing with supercharger disconnected , what it does is it will start and idle and rev up when cold but as the motor starts to warm up the idle gets worst even before it goes into closed loop and turns off even if im reving it it stalls fuel pressure is fine when it stalls and i have no codes also all scanner data reads good the only problem i know i do have is the alternator is not charging but the cars turns off before the voltage reaches 11.00 volts ive never seen a computer so sensitive to voltage if that is the problem, im going to change alt tomorrow and try again i will also check spark and inj. pulse while it cuts off ,any thoughts ?also rich and lean gauge reads stoich when car stalls so i know its not flooding . im a mercedes tech , ase master tech ,mercedes will run fine till battery dies kinda kills me that i cant fix this stupid little problem my brain is killing me please help .

RednGold86Z

iTrader: (1)

Does your rich lean gauge read perfectly in the middle for stoich, or is it bouncing back and forth? If it's perfectly in the middle, then there's a problem with the O2 sensor, because once it warms up, it never should be in the middle. Are you using a scan tool? That would help. Look for O2 sensor voltage swinging up and down, and look for INT (integrator) and BLM (block learn multiplier). If it's stalling while revving, it's likely lean as heck. Probably has INT at 80, and BLM at 108 (means ecu pulled out fuel from thinking it was rich).

Otherwise, you might have a bad ECU, due to the voltage issue.

Also, 30lb injectors from some manufacturers don't flow consistantly at lower pulsewidths (in other words, sometimes you can't get away with just changing the injector constant in the chip).

crook

blm 128 int 128 new o2 and is oscillating fine what i meant was not lean or rich tried new ecm and same problem also tried 3 different sets of injectors and both chips thanks for the response

crook

oh im also using a blaster 2 coil i wired it in right i put the white wires that went to the coil together as in the wiring diagram shows them connecting together in the coil and the other two wires together as they are the positive feeds could the coil be BACKFEEDING somehow to the module as that same wire powers the module also? i dont see any diodes in the wiring diagram in the factory coil .There has to be a reason that i dont see regular blaster coils on gm i always see the gm type msd coils any thoughts out there?

RednGold86Z

iTrader: (1)

Brain is backfiring on me (hope you didn't read what I had wrote and tried it, yet). One white wire is for the tachometer. One pink wire is from the ignition switch. One white wire fires the coil. The other pink wire powers the ignition module. I THINK. You should have both pink wires on one (+) post of the coil, and both white wires on the other (-) post.

So, just to be clear - you can try to hold the RPMs up, but it will still stall out?? And you have good fuel pressure at that time. Hold a timing light on the engine during that stall, and just look for sparks during the stall. Also, if you have a good scope, or a good noid light, do the same on the injectors. If both cut out during the stall, it's probably a power supply problem (check ignition switch and fused links, and measure supply voltage at the injectors and coil). If injectors stop, but ignition stays, that rules out ignition. How are you powering the injectors? If you're going through a relay, it could be bad. If you're just going through fuses (like factory method), maybe some other problem.

The alternator not charging may mean that it's not wired right. I did a TPI swap this winter, into a 79 malibu, and had to do some homework on the alternator wiring. Should have a two-wire weatherpack going into it. I think one wire was red (from a fusable link off the starter), the other brown?? Also there's a large gauge wire needed on the output post, that should run directly to the battery, (or starter post if you wish).

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Link works, but looks like crap for some reason.

crook

i tested the wires to the alternator they are perfect im planning on checking pulse and spark tomorrow so ill let u know yeah while im holding the idle up it deteriorates in the way its running then just dies so i know im loosing something i was just wondering if anyone had this problem before so it will save me the headache thanks alot again

RednGold86Z

iTrader: (1)

Maybe the coil is too low resistance for the ignition module, and overheating it, but doubt it. The module should have built in over-current protection. Does the engine restart quickly during this problem, or do you have to wait for it to cool down a few minutes? Might be a sign of an electrical component overheating, such as ignition module, if it's difficult to re-start quickly. Did you use the heat transfer compound on the underside of the module (if you replaced it)?

crook

no its hard to start but if i wait about 2 to 3 minutes it starts up again i havent had a chance to test the car yet ive been too busy i didnt use the compound because i didnt have any cause i switched it with a nother used one so maybe there is not enough ?thanks for the input maybe thats it ill try it tomorrow i have an inductive pickup spark tester so ill use that thanks again

crook

ok listen to this one hopefully everyone reads this keep in mind i checked fuel pressure 5 times and got 35-45 psi every time even while running so after trying to fix the running problem 100 times the car finally would not start anymore i thought yes i can finally fix this @#$t so i found i wasnt getting any fuel in the cylinder checked pulse ok then went to check fuel pressure again for the 6th time when installing the pressure connector i found only pressurized air !!!!!!! fuel guage reading quarter tank and i just put 5 gallons the day before so i removed fuel pump assembly through hole in floor ,the best way i may add, and found no fuel none nana zip zero so i reinstalled pump went got 5 more gallons and voila car runs perfect where those first five gallons went the world may never know????????? thanks to redngold86z for his help i still cant believe it damn

RednGold86Z

iTrader: (1)

Hehehe, sorry it took you so long. I once paid a shop to change a "bad fuel pump" as per my instructions (Car was stalled at a faculty parking lot at Iowa State) - couldn't smell any fuel (carbed car), and had good spark, and it snowed, and it was cheaper to tow it to the shop than to tow it to my parking lot. They put a new pump in, but when I picked it up, they told me it fired up after putting some gas in and their excuse for not telling me this was that they checked the pressure and it was "bouncing" (mechanical fuel pump, go figure).

That's the only thing I've had a shop do for my cars, except mount and balance tires and slap an OK on my DIY alignment for $70 (1LE spindles and brakes and new struts). Live and learn.