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Can't figure this thing out. From my research, sounded like bad injectors.
Swapped out injectors, no change, new dizzy, no change, disconnected exhaust after manifolds, nothing
45psi at the fuel rail, injector test light on with key on, flashes on both banks when cranking
Fuel sample looks fine. What am I missing? Is this ECM known for probs like this? Can I swap out an ECM from a 305TPI car? ECM is pushing voltage to my injectors both banks, but this car just starts and dies quickly all day long
I have a new LT1 fuel pump, should I try that? PSI at fuel rail jumps to 45 right quick with key on. Any suggestions?
Was checking timing by cranking the engine constantly, car will fire/run almost like it's running normally with the key to 'start' and starter cranking
I did have the engine run on it's own for about ten seconds (ran rough)
Pulled the drivers side valve cover and could see all the valves opening and closing
Double checked the plug wires locations on the dist. cap
The timing light flashes smooth then has big dark gaps where the engine speed falls. I'm thinking there still an ignition issue here. Could a bad coil cause all this? What else is there to troubleshoot with ignition?
I noticed the coil mounting bracket on the intake doens't fit the one on the coil. Someone has monkeyed around on this car in the past. The passenger side coolant temp sensor ground is re ran to the firewall. This engine may have been a replacement. The steering column looks like a replacement, there is a lock cylinder ziptied under the column with key in it, assuming for the security (VATS) feature. The security light lights up with key on, then goes off after a second or so, so think the VATS isn't my prob.
the intake bracket is straight 2 bolt holes in a line, the coil bracket is offset, can only use one bolt to mount the coil to the bracket
hard to see but the coil bracket angles back under the coil right after the phillips head bolt
Is that the coil mount that came with the car? The stock one is a 2 piece thing that definitely fits with the bolt holes. The DUI coil I got came with one that fit the stock coil location. It's a spare, I could send it to you if you wanted lol.
Ignition would be a suspect. Coil or ICM.
The 305 ECM can work if its from the correct year range and shares the same part # as your ECM (assuming you have a 350). You'll want to swap your PROM chip over to it.
My fuel pressure seems strange to me, key on, jumps to 45, then bleeds off quickly to 0. Then key on again and no pump running or pressure, takes a few moments before pump will run with key on again. I'm guessing it's a bad fuel pump and check valve, about to swap in the pump I have for an LT1 car
As I type that last paragraph, really think my pump is bad
Last edited by Bazooka357; 11-20-2019 at 11:59 AM.
My fuel pressure seems strange to me, key on, jumps to 45, then bleeds off quickly to 0. Then key on again and no pump running or pressure, takes a few moments before pump will run with key on again. I'm guessing it's a bad fuel pump and check valve, about to swap in the pump I have for an LT1 car
As I type that last paragraph, really think my pump is bad
If you do key on it will only pressurize for 2 seconds. If you turn the car off and back on it won't re-prime immediately. You're supposed to be cranking the car that first 2 seconds really.
Bleeding to 0 doesn't necessarily indicate an issue, as modern pumps don't use check valves. If it's an older pump, then maybe. What is the pressure when trying to crank and run, if it's low there than I'd look at the pump.
I'd start with a correct new sending unit and fuelpump.
Looking at the cut up lines on the top of the sending unit, I'm guessing you also have a trap door in the rear hatch?
Yea, the LT1 fuel pump is in. PSI jumps to 45 and holds about 40 instead of quickly bleeding off, but the car still starts and dies the same. No change at all
To fit the LT1 pump, I just whittled down the white plastic fuel pump case with a sharp knife. Wish I'd thought to take a pic before buttoning it up. I was anxious to see if it'd work and fix the car too. I just cut off the fuel level sending unit, for now.
I've got a lot more fuel pump if I need it. LS's run about 60PSI and hope this pump will do that pressure.
If someone wanted to bootstrap a fuel pump for a third gen for an LS swap, i'd think a junkyard free fuel pump from an LT1 car or Northstar, or LS truck would be fine
Almost ready to give up on the engine. 4 full days of working on it and haven't gotten it running. My tuner and my mechanic friend don't know anyone who's into third gens and good at working on them. I'm not sure where to dig next. I need to figure out what wiring is essential for my ignition system and find and check all grounds. I've found several weird wiring/grounds under the hood.
Really in love with the car, reminds me of the C7 vettes more than anything. Love this 80's feel, color combo, interior color, T tops. I'm crazy about the car.
Think I've got plenty of fuel and spark now, might pull the spark plugs and check compression next. Car sure sounds smooth during the quick start up, right before it dies.
Yea that ratchet whips ***. Im going to the JY to grab an ECM today, Looks like GM used this ECM in a ton of vehicles back then, and I can swap the prom chip to make them work. The more I learn about the car and the way to source and use junkyard parts, the more excited I am for this platform.
Been dinging around the car taking things apart and starting some cleaning. Whole thing need power washed, everything, it's coming
I
Spent time at the junkyard preparing a LQ9 for removal, getting it first thing in the morning, might just start preparing the car for the LQ9
Since I can't get it to run LOL
Havent' decided if I should pull the trans 4L65E, too and swap it all, will try to trade the trans for a 2WD 4L80E
Got the airbox, uncut harness, fuse block, heater hoses, rad hoses, ECM, coolant tank, battery tray, engine oil cooler, tried to get a lot of the support systems because Im going to need the stuff for installing into the Trans Am. Need a posi rear end ASAP. Might just use the 700R4 for now until I can source a 4L80E, kept the trans harness intact so I can plug and play when the time comes.
I want to get this thing swapped ASAP so might forego working on headers, cam etc and just try to move fast.
Pulling off the oil pan tomorrow to get started on cutting down the pan and pickup, have a look at the bearings. I need to buy an engine stand. Wonder if harbor fart has one
Got to figure out if I should drop the subframe out of the TA, it's probably the best way to go. Going to do a nice engine bay cleanup polish wax, touch up paint, love this blue paint so much and it's shining already
Really want a good K member, thinking about relocating the battery to the back. Fitting the intake and alternator is going to be fun, might buy a welder while at the store tomorrow. Wonder if they have a sale coming up. I donated 5 cans to Harvesters at the junkyard for 25% off
I got a heated and cooled cupholder out of this Escalade, didnt' even charge me for it
$265 out the door for this engine and everything, I even took the tire....
Feels like an episode of Roadkill Garage with Frieburger and Dulsich, those guys have too much fun
The engine mount bolts were monsters, red locktited in place and we really struggled, batts for the impact did'nt hold up with them. Should I have removed those long 18mm bolts that run parallel with the frame instead? I was worn out big time, A torch would make quick work of that loctite but the yard doesn't allow torches. I might sneak one in next time er something, go for those long 18mm bolts.
Feeling like taking it easy this weekend though, gonna see about removing these TPI exhaust manifolds, what a PITA, in order to check plugs and do compression tests, these things are a real problem
^Thanks
Figuring this has to be the ECU giving a weak signal, anyone know what voltage I should get at the injectors? Where the ECU gets ground? Think im going to pony up and get an ECU, can't seem to find a test unit anywhere
^Thanks
Figuring this has to be the ECU giving a weak signal, anyone know what voltage I should get at the injectors? Where the ECU gets ground? Think im going to pony up and get an ECU, can't seem to find a test unit anywhere
Any luck moving forward? I found that I can keep mine running with a steady mist of starting fluid. So even though there is injector pulse as confirmed by using noid lights, I’m also wondering if it’s too weak a pulse. The noid light lit up at each injector connector but it wasn’t the brightest light. Kinda dim if I remember correctly.
^Not yet, had to attend to other priorities. My battery/wires were in total disarray too. Next step is to clean up wires/terminals etc and check pulse volts and ground for PCM, my prob has to be weak signal. Will update
Just bought the poorkid swap mounts/pan/acc brackets so going to pull the engine. Never got it to run
Guessing ECM but rather not chase it anymore
Was getting some weird ground readings today on the ECM plugs, new battery terminal connectors and cleaned up all the grounds I could find. They all needed cleaned but didn't fix my prob
Had 12v at key on to injectors
I got the ground strap from the back of the block or heads, not sure which, ground by the battery for chassis, ground from power steering pump to batt. What other grounds should I check? I learned a long time ago that check grounds first when having electrical probs. But I kinda screwed this one up...
Ended up being the throttle position sensor being misadjusted
Wow, that’s the last thing I would have thought. So it runs like a champ now? I’ll have to look into how to adjust it. Was it easy (I ask this while drinking coffee, being lazy and asking as opposed to doing any searching hahaha sorry).
11-19-2019 | 05:07 PM
