felo72

I fixed quit a few problems with my 86 IROC with a swapped out 350 and the 305 TPI setup with some extras (I'm fixing someone elses mistakes). When the engine is cold it starts right up, after a few seconds idles down to about 650 RPM, then I put it in drive and when i push on the gass it bogs down. It doesn't stall or back fire and I could drive it, but I'm not even throwing any codes. Then when I turn the car off and try to restart it, it won't fire until I let it sit for about 20 minutes to a 1/2 hour. I've changed the ignition module twice thinking the first one was bad and still the same problem. I checked the TPS and it's at .56 volts, and I've set the initial timing in drive at 650 RPM at 6 degrees advanced. The only problem is when I hook the EST back up and start the car, the computer advances the timing to 12 degrees advance and it runs pretty choppy. I've changed many many parts, and I think the timing advancing is my problem, but what causes it? Please help, I'm so close with finishing all of the fixes, this hopefully will be the last.

felo72

Come on you guys, atleast one of you had to have heard of this.

RB83L69

What injectors are in it? What chip?

felo72

22 lb./hr injectors and an 88 350 TPI chip. I tried putting the old chip back in and resetting the computer and still had the same problem.

RB83L69

Timing advancing is not the problem. It's supposed to do that. 12° doesn't sound like very much advance though, but that's not what's causing your problem. The ECM does it because it's part of its program.

Strange specific symptoms aren't something you should expect someone "had to have heard of this"... this is going to be real troubleshooting, not a cookie-cutter parts replacement case at the dealer with a brand-new car with no wear on it. Expect to have to do a little diagnostic work, check stuff, think a little, things like that. I doubt anybody here is going to have the "magic bullet", especially sight unseen over the net, for your issue. Changing "many many parts" is a very economically inefficient way of locating a problem of this nature, and doesn't guarantee that you're any closer to a solution than you were when you started.

Your problem sounds like fuel delivery, depending on what you mean when you say "bogs down". What do you have the fuel pressure set at? What is it when it's acting up? When it "won't fire until...", will it "fire" if you use starting fluid to substitute for injected fuel? Or does it start up easier if you hold the throttle wide open and then blow a big puff of black smoke when it finally begins to run? i.e., is the hot start problem caused by a lean condition, or by a rich condition, or by ignition?

3 things are required for an engine to run: compression, fuel/air mixture in reasonably correct proportion, adequate ignition at the right time... which one is missing?

Last but not least, what kind of "extras" do you have? What happens if you make it back all stock? What other "mistakes" do you already know about, that might help point toward further as yet undiscovered ones?

felo72

Ok, this is going to be a long one. I've been diagnosing, I started off by checking the trouble codes a couple of months ago and came up with a code 33. Checked the MAF and it was bad so I replaced it, checked the relays and they were bad so I replaced them too. After I did that, I couldn't get the car to idle down, I checked out the vaccume lines, nothing, then the throttle body, an Accel 1,000 cfm model, and it was all gunked up and the butterflys wouldn't close all the way. Plus the gaskets were worn out, so I changed all of the gaskets and cleaned the TB. While reinstalling it, I installed a new IAC because the old one was rusted all to hell and couldn't be salvaged, along with that I changed the TPS and set it because while trying to set it at WOT it was real speratic. I put a new one in and it cured the problem. After all of that, I noticed the prime wasn't working for the fuel pump and it wouldn't start, plus I wasn't getting any fuel. So I changed the fuel pump relay and it didn't fix it, then I noticed the fusable link was blown, fixed it and now I have fuel. After that I kept blowing a gauge cluster fuse, tracked down every wire that leads to the cluster and couldn't find a short anywhere. Finally noticed that the coil was part of the problem. When I would start the car, the tach would peg out at 7,000 and it ran like sh*t. Tracked down the wires for the tach and noticed it was connected to the coil, changed the coil and my problem went away. Now back to what I'm diagnosing currently, car runs, but won't start when hot. First thing to think of is the ignition module, so I changed it, and it still won't start when hot and the car boggs (sounds like a carbed car when it gets too much air). I've tried the WOT while start up and nothing, I'm also running 45 PSI when it's running, and as for putting it all back to stock, I can't. The person I bought it off of put a 350 out of a 1980 Chevy truck in place of the 305, but remember I'm not throwing anymore codes. I've also put the old chip back in and the same problem persists. I hope this answers your questions, as you can see, I've been thinking and diagnosing like crazy and I'm once again stumped. I'm not looking for the "magic bullet" just some ideas of other close instances or problems other people had.

gmgod

Have you checked to see if your injectors are bleeding off after you shut it down?

felo72

I don't know how to check to see if they are bleeding off, how do you? I have however pushed the pedal to the floor while cranking the engine and it still won't fire. I do have an update, I checked the fuel pressure again last night and kept getting a reading between 35 to 39 PSI. Is this the start of a fuel pump going bad? Thanks for the help in advance guys.

felo72

Well, I got a call from my mechanic today, he said it's either the cam or a broken valvespring . I'll either be buying parts from Summit or I'll be in the market for a new engine, depending on how much he'll charge to install a new cam. As I hear more I keep you posted.

gmgod

Does the mechanic have the car? I guess he does and has done a compression check. You can check to see if your injectors are leaking with a gauge by just turning the ignition on to put pressure to the fuel system and watching the guage. If you see the pressure dropping the injectors are taking a leak most likely.

felo72

Well guys, the cam is gone and the rocker studs are beginning to come out of the heads. So now I'm going to part out the car because I don't want to put out any more money. Thanks again for all of your help.

felo72

While I was tearing into the engine to get it out, I noticed an externally balanced damper, so I looked at the flex plate and noticed that was externally balanced too. So I tore into it more and noticed forged .100 in. domed pistons, by *** it's a 383!!! So now I'm going to throw a new cam and lifters in for $130 and the heads are going to the machine shop today to get screw in studs and have the valve springs checked for $80. I'll probably get a new EPROM burned for it, but it seemed to run pretty good without a custom chip. We'll see.