I realize I'm just talking to myself now. No responses so I suspect I've stumped the panel. But I'll continue to post just in case I fix this and someone can benefit from it down the road.
I tried a new EGR valve after some suggestions in another forum. That had zero effect on the problem. Today, for giggles, I marked the distributor and tried advancing the timing. There was an immediate difference. The was just the slightest hesitation but no backfiring. Unfortunately, now it has started dying for no reason at all. Like three times in a mile. It acts like a bad ICM but I've replaced that and, yes, I used thermal paste.
I have a very similar problem to yours: takes a long time to crank, fires right up when engine is warm. But it also fires right up sometimes when it's really cold in winter. When it does start, there is a fuel smell, so I hit the accelerator during cranking, which helps the engine get air and speeds things up, but just a little.
I have replaced: IAC, MAT, air/fuel filters, plugs/wires, ECM, ICM, cat, O2 sensor (it's heated now - no change), even with the 7730 ECM and the elimination of the cold start valve crap I have the same problem. Maybe I have a sticking or leaking fuel injector, that's one thing I haven't tested yet.
I have not but it will be checked. I purchased an ALDL cable from Red River so I'm hoping to connect that soon and look around at what the ECM is doing.
I did try advancing the timing some. It ran much better but then started randomly dying as I was driving it. I intend to set the timing back to where it was and see if the random dying goes away.
I changed all the plugs and wires tonight. To the fellow who put in five Bosch plugs and left that one original AC plug on number 2 ...
I recommend running AC delco in all of them, regular plugs, not platinim or anything other than regular. Run a fuel injector cleaner such as Chevron Techron.
[This message has been edited by 2.5 (edited 07-10-2012).]
What I'm seeing is that the BLM is starting out at 128 when I crank it and immediately goes to 150. Then INT starts at 128 and then shoots up when I step on the gas. Fuel pump fading away on me?
I read the entire postings and saw no mention of replacing the least expensive sensor. ATS sensor / Air temp sensor. Its in the air cleaner box. It measures the outside air temp and a cold reading will cause the fuel mixture to richen up to avoid stall or stumble. Sort of like a manual choke on pre computer engines. If you didn't use the choke it was hard to start or if it did start without using the choke it ran like crap until the engine was warmed up.
Been a while since I used winaldl but on a cold start the ATS temp reading should be close to what the outdoor temp is. Check the archives for more info or maybe others will chime in.
Spoon
------------------ "Kilgore Trout once wrote a short story which was a dialogue between two pieces of yeast. They were discussing the possible purposes of life as they ate sugar and suffocated in their own excrement. Because of their limited intelligence, they never came close to guessing that they were making champagne." - Kurt Vonnegut
I've continued to log and have some friends look at it. They agreed the BLMs and INT values were through the roof, causing the car to run rich. I disconnected the EGR and plugged both ends of the vacuum line with no effect on the problem. I then disconnected the battery to reset the ECM. That seemed to get the numbers back to normal on the INT/BLM but the resulting drive had them creeping up again. Back under the deck I went. I found a tiny vacuum line that was not connected to the EGR solenoid switch and reconnected it. No real change to the problem. I tested the coil. It failed the third test per the FSM, going infinite on resistance. I replaced the coil. No change. I also hooked up a fuel pressure gauge and did a leak down test. It took 10 minutes to drop 10 psi so I don't think it's a leaky injector.
To sum up, it still runs like crap and I haven't a clue.
I had only been collecting sensor data in the past. This time I clicked every box for RAW data and all. Sorry to keep bombarding you guys with this but I'm stuck.
I've had the same problem with my '86 GT and never sorted it out. Haven't touched it much in the last few years but got down to suspecting the distributor / ignition. The pickup coils under your rotor go bad as everyone knows.
Sorry no help. Hope you can figure it out.
------------------ --------------------------------- John Fenton 1986 Fiero GT 5 speed
I would remove the EGR valve and check it, they can look OK at first glance but actually be leaking or faulty.
Also, change your pickup coil, its like a $15 part for the genuine Delphi one. Its a bit of labor, but it needs to be done and its only a matter of time before it fails. A new one improved the drivability of mine
I may have missed it, but have you checked timing with the diagnostic terminals jumped? Replaced cap and rotor? I doubt the TPS would cause hard starts. How are your grounds? Measure resistance from your engine block to the battery negative terminal. It's not a bad idea to take apart as many connections as you can and clean them and apply dielectric grease - they've certainly corroded over the 24 years since the car was built.
The fuel injectors probably could use a good, professional cleaning too.
The EGR valve has been replaced. I replaced the coil this past weekend after it tested bad. TPS seems OK based on the logging I've done. Grounds would be a good check to do. I haven't done that yet or hung a timing light on it. I'm starting to wonder if the pickup coil is getting flaky. Thanks for the ideas. Keep 'em coming guys.
I didn't read every response but have you eliminated the cold start injector and/or the sensor? Sensor is on the front of the engine by the fan sensor. Sensors off any 2.8 MPFI will work. New ones are over a hundred bucks!
[This message has been edited by raysr11 (edited 07-17-2012).]
I recommend running AC delco in all of them, regular plugs, not platinim or anything other than regular.
I agree with this if you have not, but I would add that you ensure that each plug is correctly gapped. Also I too had the same problems you had with the BLM and INT. when I bought my car from a used car dealer he claimed to have done work on the car includeing changing the plugs. Turns out he only replaced one and out of the 6 there were three different types of plugs in the car and all were incorrectly gapped. When I replaced them things it was like having a new car.
I have already changed the plugs to AC's and gapped them myself on install. No difference.
I'm home now from the POCI convention. I saw some great Fieros while I was there but never saw an owner around. If anyone in this forum was there, kudos on your cars.
I hooked up a fuel pressure gauge tonight and had my wife drive while I watched the gauge. It varied from about 36-44 psi while we were driving. 36 at idle and 44 as she nailed it. Does that sound about right to folks?
I'm going to start driving it to work and back. If that sucker dies at least I'll have a smoking gun!
I did a leak down test. It took 10 minutes to lose 10 psi. I didn't think that pointed to a leaking injector. That seemed fairly normal to me. Am I wrong?
Your BLMs at 150 scream that you have a trouble. You say you think it is rich, but I disagree. The ECM is trying to add much more fuel compared to it's base programming. You can assume that is because the O2 sensor is showing the engine is running lean. You can confirm this by unplugging the O2 sensor and resetting the ECM. Then take the car out for a drive. The ECM will then run open loop, and will be running on it's base (128 BLM) settings. If the car runs worse (or about the same), you can assume the engine is running lean.
So to be clear, it looks to me that your engine is running way too lean.
GM does not allow the ECM to adjust the mixture too wild with the BLM function. BLM is supposed to only fine tune a already correctly running engine. Also the BLM's are limited in their range. That is why you are seeing them topping out at 150.
A double check would be to pull the plugs and see if they are black. If they are white, yes you are running quite lean. Your poor throttle response is also an indication of being too lean. You would be kicking out a fair amount of black smoke to get poor performance from being too rich.
So what is giving you this too lean condition? Most likely still partially plugged injectors. That is pretty common with an engine that sat for 2+ years.
Take off your upper plenum. Unplug the wiring from the injectors. Unbolt the fuel rail and lift the rail with the injectors still attached out of the lower plenum. Then hot wire your fuel pump to run continuously. You can do this by unplugging the oil pressure switch and jumpering the two far pins of the connector together. (The middle pin is the oil pressure gauge). Now one injector at a time, fire the injector by applying 12v across it's terminals. Look at the injector spray and compare them injector to injector. I would expect you have multiple injectors that have weak or no spray.
You can attempt to clean your injectors by soaking the tips in injector cleaner. Many have had good results that way. Totally stuck injectors can be unstuck by rapping them with a screwdriver handle.
Injectors are not meant to be energized for long periods of time, so don't do that. Don't make sparks near the injectors or you might burn yourself up. You can use just a 9v battery if you want to energize the injectors. Keep your fire extinguisher near always when working with fuel.
Replace the O rings of the injectors, along with the upper to mid plenum gaskets when assembling. Before putting the upper plenum on, pressurize the fuel rail and check for leaks at the injector O rings.
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I hooked up a fuel pressure gauge tonight and had my wife drive while I watched the gauge. It varied from about 36-44 psi while we were driving. 36 at idle and 44 as she nailed it. Does that sound about right to folks?
Yes it does sounds very right. About a delta of 42 PSI across the injector from fuel rail to intake manifold. Stated a different way - About 42 PSI minus the intake vacuum pressure. Intake vacuum drops to zero when the wife nailed it. 44 is close enough to 42
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I did a leak down test. It took 10 minutes to lose 10 psi. I didn't think that pointed to a leaking injector. That seemed fairly normal to me. Am I wrong?
Yep that sounds fine. Again however it seems that your problem is too lean, (stuck shut injectors), not too rich (leaking injectors)
[This message has been edited by phonedawgz (edited 07-25-2012).]
Good information there. It would be this weekend before I could tear into the top of the engine to get at the injectors. I'll do some research on steps to do that and possibly try on Saturday.
I did drive it to work today. I data logged it. It started, died, then started again and ran like crap. I almost turned around and went home with it but decided to get out of my neighborhood before I decided. It was cutting out, but no back fires. After a couple of miles it started to smooth out. It has a new trait. While cruising along at a steady speed it will buck, act like it's going to die and then keep going. Weird, huh?
I haven't looked at the logs yet. Work has me hopping today. I'll post a link to those when I can.
The second log is when I was cruising along and it did that buck/die thing, right at the end. Look at line 41 and see the BPW number and the rich/lean column. Another thing I notice in both logs is that since resetting the ECM the BLM numbers seem to be staying at 128 now. WTH? The INT numbers are up there but I'm not sure if that's normal or not.
So a few things. The ECM fires the injectors based on the ignition signal. So unlike a Carb - a FI system wont backfire on a drop of ignition. The first thing to check - does the Yach drop out when the trouble occurs. If so this is a primary ignition problem.
Try B-12 chemtool in the gas tank -> then change fuel filter. (it's more aggressive) But use Seafoam in the vacuum lines, common agreement is that chemtool is too aggressive for vacuum lines, or crank case
I can see where sucking the SeaFoam in via vacuum might clean the intake/combustion chambers but how is that helping injectors? Do the vapors hanging out in the intake plenum cause varnish and such to break down on the tips of the injectors?
And of course when you need it to buck so you can watch the tach, it won't do it. Drove it home and didn't have any issue except that 1/4 tank it showed on the gauge suddenly turned into 1/8! YIKES! I was scared I'd run out but made it home. Time to dump some in from the gas can.
I did notice that with the gas that low when I went up a hill or left a stop sign the gauge would go past full and then fall back to actual fuel level.
Started checking off all the stuff on the FSM diagnostic chart tonight. Possible causes eliminated were the alternator, 14.5 volts output, the purge canister, pulled all the lines and plugged them, started to check timing, but the car was not fully warmed up and it was 106 F. here today. I wasn't staying in the garage an waiting for it to warm up for that. Quick check showed it was 4 degrees retarded but it was cold and not in drive (auto) so I'll do it right and report back. It's looking more and more like injectors. Oh, and now it's started dying when you put it in gear until it's warmed up all the way. Then when you put it in gear it the idle drops way down and recovers. Not the TCC. Fixed that already. And it doesn't die at stop signs. I will disconnect it to confirm this but I burned my arm once tonight. Not going back to that until it cools off!
[This message has been edited by Super Duty Critter (edited 07-26-2012).]
I had the same problem in my 88 with a 2.5. I gave up on finding it & took it to a mechanic. It turned out to be throttle body gasket. Cost me about $150. I wish I had given up sooner with it being that cheap.
I tore down the console because the shifter jammed. I'm now 78 cents richer. Fiero's are, I learned, notorious for getting spare change under the shifter and jamming it. I had to disconnect the battery to be safe while doing this and, besides, I wanted to see why that ALDL connection wasn't mounted down. Other than the screws missing from it everything looked pristine under there. Right down to the stock ECM.
I hooked the battery back up and cranked it up. It started hunting for idle again. I gave the ECM a few slaps with no effect, just checking for loose connections. Usually, after disconnecting the battery, it will hunt for idle a bit, run high idle and then settle down. It did that again this time and immediately threw a code. It was a 44 which is EGR detecting a lean condition. I ran through causes and it looks more and more like bad injectors.
Ran like a sewing machine on the way home from work. Just the tiniest stumble when I started it. But the temps were in in the mid-90's here today. It's weird. If the air temp is in the 90's it seems to smooth out.
And I have to say, I do love driving a Fiero. They're unique and handle well in traffic. It's just more fun than driving one of those foreign built cars where they all look like they came from the same mold.
Make sure your MAT sensor --that's the one on your air filter canister- is connected and check the impedance of it. BTW: It's a very cheep sensor to replace. A faulty can confuse the ECU and screw up your A/F ratios at diffident temps.
