92Formula94

Third Gen, Hello. Looks like I am new here, however I was here before. Had a few third gens a few years back but can't log back in for the life of me. Having an issue I have been chasing for a long time.

92 Firebird Formula
305 TPI 5 Speed.

You guys may have seen someone else having the same issue with this car. This car is my old car a few years ago, I got rid of it to the guy who had posted about this issue a few weeks back. Since than, I have gotten the car back.

History on the car, it's on its fourth 305. First three motors blew up and GM replaced them within warranty. This fourth motor I put in and went through and rebuilt the motor from top to bottom. An all OEM build. The car is on it's third T5. I rebuild the trans as well at the same time. Trans is perfect and has no issues. An all OEM build as well.

The issue I am experiencing is this, about a week ago, the car firing up great. And ran okay, however on acceleration hesitated pretty badly. I changed the fuel filter. Fired the car up, and it ran perfectly, lots of power, ten minutes later started having the same issue. So i cut the old fuel filter open and it was full of garbage from the car sitting for awhile. So then I figured I would have to drop the tank and clean it out because I assumed it was clogging filters hence why it ran great until it got clogged again. Changed the filter again, same issue. After ten minutes car started running bad. Cut the filter open again, and it was perfect. Not a spec. Did this a few more times. Exact same results. So I have eliminated fuel for now. Now I am onto heat. Once the car gets warm, and this car reaches operating temps very quickly. It starts running horribly. So I figured this could be the coil. It resembled coil issues. Runs great until it got hot. Replaced the coil with an MSD coil. Ran great until it got hot. So I temp checked the coil with a gun. Was over 150 degrees which is usually when they grenade themselves. Replaced this coil with a street fire Msd coil. Same issues of course. I decided I would relocate the coil because the factory location is in a spot where it gets hot. I pulled a coil out of a 94 chevy truck. Set it up on the air dam and let her idle. She idled better than ever. I wasn't able to drive the car like this because it was my brothers coil and he wasn't willing to let me possibly grenade his coil. So I went and bought an OEM BW coil and relocated it down by the overflow. Car ran horribly. Bucked, hesitated, stalled, backfired loudly twice, not just the little popping. Couldnt get over 10 mph. I realize the longer wires are, the more resistance they create. However I don't think this is the issue because the wires and coil wire are longer now sense I relocated it. Whatever the issue is, it is continually getting worse. And now I have had to park the car and can no longer drive it. Throughout this mess, when I replaced the coil I also replaced the wires with MSD wires and got an Accel performance cap and rotor. It definately needed them, however wasnt the issue. The car has a new top shelf distributor as well. New Map sensor, new IACV, intake manifold was leaking so I replaced all the plenum gaskets and manifold gaskets. Timing is perfect. Tripple checked firing order. Distributor is where it needs to be. Car is all stock echaust for full flowmaster true dual exhaust, no cat, flowmaster 40 mufflers. Also, oil pressure tops out the gauge. At 60. So, i ordered an ICM, it'll be here today and am going to try that. What do you guys think? Also, tps is right where it needs to be, cold and hot readings are good. Thanks guys, I am determined to get her back on the road today!

TTOP350

iTrader: (8)

OHM check the injs and make sure there is no junk in the top of them.

92Formula94

Put the ICM in, fixed the backfire issue and erratic RPM problem. Going to ohm check the injectors now, now that the serious problem is fixed it will be easier to chase this problem because it is not as severe. Now just hesitating as it would if a injector was bad on acceleration. Just took her for a drive, once she got to full operating temp, she died. Took a minute to fire back up. Will check resistance, and replace if necessary. I will let you know. Thanks.

Damon

Coils don't often die. They are usually murdered. Ignition module/entire distributor is the next usual part to replace. The "lightswitch" behavior in drivability tells me you are in the right ballpark looking at ignition issues, but not necessarily the right ignition parts.

92Formula94

When the car dies, it is definately a lightswitch behavior. I had an extra new TPS lying around so I threw it in there tonight just for fun. Nothing. I will try the distributor, it has a brand new one, which often means nothing. I replaced with a very nice one. cant remember the brand. I have the old one which was still operating fine. I'll throw it in there tomorrow afternoon and see what happens. Probably was the factory distributor. I replaced it because the chassis has 220k. But I know it worked. If it fixes the issue I have a lifetime warranty on the new one so I will be fine. I will ohm check the injectors if this doesn't fix the issue. However I don't think it is anything in the fuel system. It would bog before it dies usually. I have heard of injectors having issues when they get hot, but it has never happened to me personally. I'll let you guys know what I find out.

92Formula94

Last night I ended up just buying a brand new richporter distributor. Through her in, gonna re time tonight and update you guys. Strangely enough, before I pulled the old one out, i lined up TDC rotor pointed at first cylinder. Pulled her out, new one slid right in. And was about 10 degrees more retarded then where I had it before.

92Formula94

Hey guys, also...in changing the distributor I noticed that there is a vac line back there that has been cut. Looks like a sensor going to two small vac lines ending with one bigger one. The bigger one is cut and leads to nowhere. What is this? This an issue and causing my problem? Hence, it is right next to the distributor. It's connected to The mount for the original coil.

92Formula94

Never mind. I believe if I remember right, these are for my EGR. this won't help my current issue, but will most likely relieve my EGR code

TTOP350

iTrader: (8)

Yeah, just unplug the EGR electrical solenoid, boom, no more light.

92Formula94

New distributor installed, still hesitates. Doesn't die anymore. Moving onto fuel, I believe the car had several different issues. Some of these parts are helping, some of them have been unnecessary. But that's okay. I'm doing okay on money and am enjoying putting new parts on my car. On the plus side, the distributor is free because the parts store is taking the old one back for a cash refund. Moving onto injectors, i'm not even going to check them, I am just going to replace them. They have 220k miles on them because I have never replaced them through any of the motor swaps or rebuilds the car has lived through. So, it's time. Now that all the other issues are fixed, it seems exactly like a lack of fuel hesitation. I did throw a new fuel pump in a couple years ago. I really hope its not bad again, I welded in a true dual exhaust, which is very much in the way of a fuel pump job, because I welded every connection, didn't use any clamps I sometimes regret this, but it looks so clean! What do you guys recommend for injectors, I have my eyes on some, and am not willing to pay 560 dollars for a set from a parts store.

TTOP350

iTrader: (8)

Southbay is a sponsor here. Good deals too. Check them out

92Formula94

Found a great deal for brand new in box 19# Ford 5.0 injectors. These Will work correct? Look identical, made by bosch. Just want to make sure. I think I could grab them for $60.

TTOP350

iTrader: (8)

Yup. Fit right in. Have run ford injs on several projects

92Formula94

Great, thanks for clearing that up. I was confused because some people say they are better for 350's. Because they are rated at a different PSI base. Didn't make sense to me, as they appear to be the same and are made by the same manufacturer.

92Formula94

New injectors are in. Happy with them, they are very loud and working great, Wasn't the issue though issue is definately to do with the fuel pump. Tonight I took her for the drive after I got the injectors in, still hesitating and died again. This time when I tried to fire her back up. I couldnt hear the fuel pump priming. Then went from off to on back and fourth until I heard her prime, car fired right up. Hesitating the whole way back. I have the car parked at the folks house, which is an hour away so working on it only happens when I get the time. This really cant be the relay correct? Only asking because I dont have a way to test/replace right now as I dont have the car with me. If it was a relay it would either, work or not, correct? Because it is working poorly (hesitating etc) It has to be the actual pump failing....right? Thanks for the help guys!

TTOP350

iTrader: (8)

The fuel pump won't prime every time you hit the key. It has a timer on it.

You need a good fuel PSI gauge taped to the windshield so you can drive the car and watch the psi.

92Formula94

Good info on the timer, I didnt know that. Thanks, now that you say that it makes me wonder if it is even fuel related because it still has a lightswitch effect. I have a good guage, I will probably make it over there today and give that a shot. I doubt it is the problem. Any chance this is in need of a new computer?

TTOP350

iTrader: (8)

Do the wiggle test on the fusible link wires down by the starter. I have had to fix the factory connections down there on several cars.

92Formula94

I tried this before, but I will try it again. Also, IACV when bad causes hesitation on acceleration. I put another one in the car. I do not remember whether it was a new one or an old one I thought that worked. I did check it with it out of the housing while the car was running and it seemed to be working fine but I found another one still in the box. Might throw that in there today also.

92Formula94

New iacv, no changes. Fuel pressure good. Harshly wiggled fusible link with no changes. Holy moly, gonna pull my hair out. Let me ad, I believe this motor in the car was originally for an 86 car, or an 89. Not positive which one but positive it is not from a 92. I also know there is a connector near the rear of the intake manifold that goes to nothing. Probably a small difference betweeen the two years.

92Formula94

Couple more things worth mentioning, I guess. Idles at 900 which is where i want it. This is when I fire it up cold. After driving it for a minute or so, she will stick at 2k, but I can kick it down. When I push back on the throttle at the TB it goes back down where I like it. This to me is an un related issue. just wanting to mention. Going to address this when I fix my main issue.

92Formula94

Im going to recap everything that I have done and try to make sure I havent missed anything.

Pulled motor from 86/89 trans am, I cant remember what year.
Motor was rebuilt.

New plugs before I dropped the motor in.
Msd wires
Cap
Rotor
Ignition coil
Several fuel filters
ICM twice
TPS
IACV
Map sensor
Richporter distributor
Brand new injectors
Tried unplugging the EST and driving, some people have luck with that and it would have helped narrow down the issue but if anything it made things worse.
Cracked gas cap, (old trick) nothing.
Wiggled fusible links by starter, nothing
Shook computer while car was running and nothing.
Replaced intake manifold gaskets and plenum and runner gaskets three times. Car runs good for the first WOT pull but once I have her in second/third it is hesitating by then.

Its "POSSIBLE" that I may have cracked a plug dropping the motor in. Very doubtful though.

Next time I get to the car, I am going to change the plugs with new delcos, and see what they look like. I'll be checking to make sure none of the wires are burned from the exhaust when I pull plugs. I checked as much as I could today on top and under the car without pulling them off and they all look good.

Any other suggestions?! Im going crazy!


Checked fuel pressure with key on, with motor running and while driving the car. Always right where it should be.

Issue is that the car is hesitating while accelerating. And dies sometimes.

TTOP350

iTrader: (8)

The wiggle test on the wires requires more than just a wiggle. I had to cut the factory plastic crimp apart to fix them because the fault was internal.

Have you tested the pickup coil and the regular coil?

jukehero

if it only screws up when it gets hot it might be because that is when the computer goes into the closed loop mode.

jukehero

what about the O2 sensor?That can screw things up pretty good once it goes into the closed loop mode.

92Formula94

Yeah, I have thought about the possibilities of closed loop and what happens to the computer etc. But the car isnt getting hot enough to go into closed loop before I start having issues. I dont have an o2 code, and when they go bad they do not match the issues I am having. At this point it doesnt hurt to look into it, and they are easy to check. Probably not the issue.

TTOP350, i will cut them open and replace. Thanks for all the help and info, it hurts my heart to just see her sitting with the nice weather, under trees getting pitch dumped on her. She just wont make the drive back to my house.

92Formula94

Also, yes coil is good. Replaced with several different options, tested to make sure it was working properly. Pickup coil came with new distributor.

92Formula94

Update, TTOP350, replaced fusible links, through in new ac delco plugs in, pulled my old NGK's. Those delcos are an inch longer than the NGK's. Bought MSD super conductive 8.5mm wires for it, just because. Heat wrapped the fusible links and wires down by the headers. And the car is fixed no hesitation and no dying. Thanks TTOP!