Not a ThirdGen, but GM 2.5L 4-banger/TBI300. '84 Fiero, 8-bit 4KHz processor, no IAT sensor (by design), experiencing intermittent stalling, poor idle, no restart. Had it towed today and almost stopped at the recycler on the way....

I have retrieved all of the following DTCs in one trip:

Code 12 - (DUH);
Code 13 - O2 sensor signal loss or problem;
Code 15 - CTS low temperature fault;
Code 33 - MAP pressure low (vacuum high);
Code 34 - MAP pressure high (vacuum low - *the opposite of above);
Code 44 - Lean O2 sensor reading;
Code 45 - Rich O2 sensor reading (*again, the opposite of above)

Bosch oxygen sensor is a few weeks old, Delco MAP is new, distributor is new, fuel pressure is 19 PSIG, CTS meters O.K. compared to gauge reading of coolant temperature, injector (all ONE of them) is new, IAC is clean, TPS is new, all gaskets down to the crank are new, all hoses are in good condition or new, ECM is well grounded, engine ground straps are good, positive bus voltage is 14.4VDC at idle, ECM connections are clean and tight, timing is 2° advanced beyond OEM base setting, fuel tank is 3/4 full and fuel is fresh 94 octane.

PROM is stock, compression is good (150), plugs are new and correctly gapped, wires, cap and rotor were new with the distributor. Coil has been changed.

I'm running out of parts to change and ideas. I'm getting frustrated with this piece of S**T TBI system, and it's unreliable, assumptive nature. I'll take a MAF any day. This system is as about as sophisticated as a f'ing wick stuck into a can of raw fuel and draped into the intake. I've had better luck with even the worst example of carburetion, the Holley 4BBL 4160. I'm about ready to send a thermonuclear token of my appreciation to the GM powertrain boys in remembrance of this fine engineering example.

How the f''k do you get these things to run worth a rats ahss?

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Later,
Vader
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"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Closest I've ever been to one of those fireboxes, was a PickNPull...that said, with the codes you're getting, and abundance of....I've leave the scan tool plugged in to monitor and see what shakes.

Was the CTS measured across it's thermal range?

 

This may sound primitave, but can you give the ECM a good whack with the palm of your hand while its acting up??

I've seen the computer have intermitant "wierd" running symptoms. Usually a good whack will change it.

I also just had a GM module (of all things) today cause rough running/missing/eratic idle and then stalling. It would only do this COLD (??) Hows that for wierd?? Warm it would run great.

Other than that, it sounds like you've got it covered man......

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ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

Are there any other common ground points that are bad (besides the ECM ground and engine ground strap)?

 

Vader, I think I'd have to go along the route of getting that ECM changed out. With as many fire-damaged Fieros as there in the local scrap yards, I'm sure you can find a suitable replacement. Good luck and let us know what happens. - John '89 L98

 

Hey Vader, I second Engineboy's recommendation of whacking the ecm while it's running. I learned this little trick from my old shop boss while working on a Assan(Nissan) pickup truck of all things. It wouldn't stay running right no matter what we tried, and it turned out to be the ecm. Every time we tapped on it, the motor would run better or worse. The ecm for that piece of junk cost like $800 new. Thank God for junkyards!



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89RS w/350 TPI; 69RS/SS w/450 HP 350/Muncie 4-Speed "Too weird to live, too rare to die."

 

vader no idea about your problem but i might be able to help out with the transuranics. ought to have soem laying around the shop at work.

disclaimer: to anyone that knows what a transuranic is it's only a joke i couldn't get any if i wanted, really i couldn't

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ICON Motorsports
1st & 3rd

 

oh yeah vader given the nature of these cars to burn i'd insure real good and let nature takes its course.

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ICON Motorsports
1st & 3rd

 

Me Too My car was running like crap so i limped it to the GM tech down the street and he smacked it and it ran fine.

 

Ed,

All the licensed ones are insured, collision, road service, and all. And none of them have burned yet, but I'm tempted....



I know about the "tap test" on the ECM, but I'm a little unclear on the procedure. Do you start with teh 12Lb. sledge at the front glass or deck lid? Or do you go right for the 18Lb. "Big Bertha" pursuader through the roof window?

Actually, the ECM it's running on is from one of the donor cars, since it's getting the spare 355 this summer. It does the same with either ECM.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited January 03, 2001).]

 

There's just something about the 'ol Fonzie trick. Once in a blue moon my ignition wire goes on the fritz and a good slap under the steering column does the trick.

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89 Iroc-Z LB9 305 TPI auto 2.73 posi:
3" Dynomax "cat" back,K&N filters, TB bypass, 3" pipe in place of cat, cleaned and flow-matched injectors, 180' thermo, mild ignition mods, synthetic oil, kicker sound system, soon to attempt engine swap...

 

My Question, For You Vader, is Why Do you have all those Damn Feiro's ?



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60 Ranchero - Project ( Money Hole )
85 Sport Coupe LG4 - Daily Driver

Livin' the Stereotype

 

Bort,

One for each foot, and a spare....

- - - - - - - - - - - - - - - - - - - - -

Ed,

Sorry, I'm a little slow. It took me a minute to catch that one. Aluminum powder has always been a favorite "filler" of mine, but it's pretty closely regulated, too. You can get about two pounds a year for "scientific" purposes before the men in black start asking questions.

- - - - - - - - - - - - - - - - - - - - -
O.K. It looks like it's time to swap ECMs again. It's too bad, since I was planning to use the last spare in a little "experiment" for the Red Devil.

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Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

[This message has been edited by Vader (edited January 04, 2001).]

 

The consensus seems to be it is the computer and a hammer is the appropriate tool for the job. This is my favorite tool. My second favorite is a bigger hammer.

 

I also agree, give that there ECM a good ole' whack and see what she does. Don't knock fiero's guys, a friend of mine has two of them, neither one to be taken lightly. Ever see what an LT4 looks like in a 2400lb car for a 5 spd stick and 150HP shot ready to go? It produces 1.6 60ft times, with tire spin, and high 10's in the 1320. If that dosen't "Fit your fancy," maybe you'd like to try the twistys with a turbo 2.8L fiero (with the newer aluminum heads on I beleive the 3.4 and may other mods) that pulls a whicked 1.1-1.2G in laterial acceleration (Gtech). Most fiero's suck, but some have been made into FINE toys.

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86 IROC-Z, Retired for winter, weird oil leak (drains out in about 3 minutes), new 355 other than that, TPI, 700R4, edelbrock headers, removed AC/Air pump, heater plate conversion - no heater (loL). 14.8@90MPH

Next project (think I'm going to scrap the IROC)- mid 80's monte carlo, 383, edelbrock performer RPM intake, cam, holley double pumper carb, sportsman 2 heads, NOS. Hoping mid/high 12's on motor, mid 11's on spray.

[This message has been edited by Slow Iroc (edited January 04, 2001).]

 

Vader,

Grind up some charcoal, a touch of sulphur, a smidgen of salt peter, and mix with nitromethane until you have a paste. Then, let it dry, re-grind it into a powder form, and.......

Turn the Fiero over by hand until 20* BTDC. Then, remove #1 plug, pour gooooood healthy dose of "magic powder" down the hole, and stand back.

Hop into drivers seat, turn the key to start, and................

Yo, Vader...........you still there?

You okay??


BOR

 

WTF vader? is that black car in the garage a *gasp* MUSTANG?

hehe sure looks like it to my eyes.

Good luck on the ECU problem you are having. My ecu went bad once in my IROC, and it wouldn't even FLASH me codes.

The conflicting lean/rich codes make me think that the ECU could be bad. but as you well know, im not a real tech here.

hope i helped!

(is that a mustang?)

 

I believe thats an impala SS sitting in the corner (thank god!)

 

So you get teh same codes with either ECM, too, or it just runs like crap with either ECM?
It sounds like you have most all the bases covered. The only thing I can think of would be the sensor ground. I'm not sure on the "P" car, but I think it is usually at the same spot as the ecm ground, but if not, that may be something to check out. Also, how about the +5v reference voltage? It sure sounds to me like some weird electrical connection problem! You may want to monitor the sensors that you got the code from, and see what all the voltages are.
I actually like these systems, because of the simplicity of them. I also have had excelent reliability with my daily driver (86 Olds Ciera) that has the same system. They are basically the same as a TPI system, just less to it!

Well, I'll put a bit more thought into it, and maybe I can come up with something to help out!

Good luck, and run fast if you see BOR coming!

------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

 

yep mr vader has a impala.

BOR that's some good stuff there, reminds me of the out house, fertlizer, and fuel oil thing vader had going on. i sure miss you posting on here.

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ICON Motorsports
1st & 3rd

 

whew! that was a close one!

i do like the older mustangs a bit, but the new ones are rice-level in my taste.

 

Box!

Good to hear from you again. I'm not quite ready for the "outhouse removal" method of problem resolution yet, but the though had already crossed my mind as an option....

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Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

JP,

I haven't driven the car with the second ECM in it yet, but have idled and run it in the garage. It runs about the same, but I realize that the BLM hasn't had a chance to writr new fuel tables yet. It runs like a Plymouth with either ECM, and I'm thinking I'll have to try the third "reserve" ECM since I have it available. I'm fairly sure teh accident that banged it onto my front lawn in the middle of the night didn't do th econnections any good, but I can't find anything obviously wrong.

Incidentally, I'm all ready for Box O' Rocks. I'm planning to dupe him into trading three of my red sporty cars for one of his blue sporty cars. That should be a pretty good deal for him, right?



------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Merl,

Actually, you're half right....




------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

vader BOR might not agree but i figure a sporty red car is way better than a blue sports car.

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ICON Motorsports
1st & 3rd

 

Vader- couple of things I could suggest. First off, if the chip IN THE ECM is the wrong chip for the job you're definitely f-ed.

Second, if you really want to talk to the Fiero expert, you need to talk to my brother. He's running WAY modified 87 GT that sports a 3.4 quad cam Z-34 motor that gives local Camamros and Mustangs fits (Whips my 94's a$$). Oh yeah, it'll pull 1.35 on the skidpad, too. All using a stock ECM (actually a hybrid of 2 ECMs running the mess).

Don't expect miracles off the bat. He's meticulous. And a lot like a pit bull- he grabs a problem and won't let go until it's SOLVED. Not worked around- SOLVED. Taught him everything he knows. Of course he's got about 30 more IQ points to work with than me, but those are the breaks. Drop me an email if interested and I'll see if he's available.

 

Damon,

Excellent point, but one of the PROMs is the original that came with the car, another of the "spares" is an identical burn number/revision level, and the third is a newer year but the same ECM, so I can install the original revision in it.

Actually, I don't know if it's the spare ECM or the fact that it's been above freezing for the first time in a month, but the little POS seemed to run better today, and I only got one DTC briefly on the way home from work. I need to check the code for more ideas, but I think I might be getting closer. Either that, or I'm still looking at a custom PROM to tolerate the work that was done in colder weather.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

Okay, 2 Impala's, 3 fiero's, most likely an Fbody someplace...WHAT THE HELL DO YOU DO FOR A LIVING! The insurance total alone would kill me.

 

Intergalactic overlords are not a dime-a-dozen, you know. We demand a pretty high salary these days....

Actually, I suspend the insurance down to comprehensive coverage for about five months a year on those that get stored, or it would eat me alive, too. The multi-car discount adds up, too. I still get a personalized card from my agent every holiday, since i think I might be personally responsible for putting all of his kids through Yale.

BTW - My new (month old) oxygen sensor is now apparently failing, or at least the ECM thinks so. I pulled a '13' from ECM RAM earlier. Ground is good, and the wiring connector at the O2 looks/feels good going together. Looks like the ECM or ECM harness theory might be right.

------------------
Later,
Vader
------------------
"No matter how hard you try you can't stop us now"
Adobe Acrobat Reader 4.0

 

O vainglorious and voluptuous vixen of vindictiveness... nonono, sorry, that was for Elise Lannister, of the House Lannister, who wed... oh never mind...

O disparate dispatcher of devilish delights... I have tried this one I thimk, however my best guess was the grounding system. It runs better cold? mayhap a ground via threading? As the nut gets tighter (assuming disparate contraction due to the shape of the metal)the connection gets better? Is this the same baby bird that got thwacked? Mayhap you have checked the wiring to the starter? (Can you not in all reality call the positive side the ground as the flow of the majestic devilry emanates thus?) Just another thought, I do find it a tad difficult to believe that three ECMs are wrong, yet the possibility does exist.


I have been good (sic), however, that all depends on your point of view now doesn't it? How about I give you a fieri facias for a nice ol' Y-body, that way we don't have to harass ol' BOR and his saltpetre (y'know, he never mentioned if it'wer the sodium, or pot. kind, probably the latter though... )


Hmmm.... I seem to keep running into this often on this board. Can't say as to discriminatory remarks, but how about bigotry? My philosophy is, if it has four wheels, is American -AHEM-, can be motivated, and has the misfortune of falling within my grasp, I'm gonna make it a firewalker.

Ede, you know I had a very interesting book that dealt with those, and I was really getting into it, unit these guys with big guns and black suits burst in yammering on and on about some bloody thing or another. Y'know, I think they kept saying 'stable' and '134'...

Edit: y'all know we need a spell checker right?
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"Harnessed Evil can indeed be used for Good, however the corruption that inevitably takes place forges a more sinister and chaotic Evil that far outweighs the good intended at inception. Thus are the first steps toward the chasm of the Dark Side."

-Me

[This message has been edited by Red Devil (edited January 05, 2001).]

 

red devil funny you should say that about the transuranics. i didn't think anyone on here would know what they were and i'm not saying, or telling where i work or what i do i've been thinking about a small power unit that i could fit in a f body using some of the stuff we throw away.

disclaimer: i'm really a dumbass that couldn't find my *** with both hands in the dark. it's all a joke.

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ICON Motorsports
1st & 3rd

 

Man, i knew u know a lot about cars Vader, but i didn't think you'd have a whole (evil) fleet of GM products!!! HA, thats hardcore. (no wonder he know so much about cars...)

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--Steve S-- 84 Trans Am 305 (cough)LG4(cough), 5 speed, Flowmaster 80 series, otherwise an emissions restricted slow 150 hp(chilton rating) 240 torquer that needs RELEASE!!!!

P.S. Daily Driver

 

O Searing Scarlet Satanic Sultan,

You are of the same mold as I - cunning and devious. Pay attention, my apprentice, and you will become strong with the Dark Side...

In other words, I suspected that, too, and all grounds have been given the once-over, but twice couldn't cause any harm.

Excellent point. I should be looking at the positive power nodes when inspecting the grounds, to be sure. And since the darkest secret of the mystic force that flows within copper and gold is that the force actually emanates from the ground and flows toward its presumed "source", perhaps I should be studying the problem from the opposing perspective.

Yes, this is the same famous flying Fiero I found floundering on the front fauna one fine friday. I still suspect a correlation, but haven't found it (yet).

Actually, I've only used two of the ECMs. The third is still sitting on my desk since I snapped the photo of the components I will be changing.

The spell check feature of UBB would be convenient, but our frequent use of technical terms and acronyms would cause a lot of nuisance corrections. Still, it would be a nice option.

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Later,
Vader
------------------
"I cannot take this any more... Saying everything that I've said before..."
Adobe Acrobat Reader 4.0

 

Thanks for all the help and advice.

I pulled the second ECM and checked the connectors. I also reseated the connectors at the engine bay bulkhead, one of which was suspect. I opened and inspected the first ECM and found nothing obvious at the edge connectors, then reassembled everything. This is about a 45 minute task on a Fiero - like everything else.

Upon startup, the ECM should have been "dumb" (all BLM tables should have been cleared), and it should have started on the base fuel tables. It started, ran at exceptionally high RPM (2,700) for about 1-1/2 minutes, then set a DTC. I shut it down and retrieved a '45' (error code, not Colt 1911A). I removed the air cleaner and started it again, and noticed the injector that I had installed about a week ago was dribbling instead of producing a nice, regular cone of fuel. Shut down again, installed the spare from the donor/parts car, and everything is now back to normal. Car is now running on the original ECM, PROM, injector, and O2 sensor. I now have several new parts that I probably could have done without because I assumed the replacement injector was good.

Fuel pressure is still at 19 PSI because of my head mods, and the car is back to it's normal slightly lean self.

Again, thanks for all the advice, and don't forget my frustrating lesson - never assume that the replacement parts are O.K., since a percentage of them are not.

I had been getting a 13, 33, 34, 44, and 45 DTC. I believe I caused the 33 and 34 when I was experimenting with the MAP sensor. Disregarding those, and understanding that the remainder of the codes were related to fuel mixture, it all makes sense. The unreliable injector was varying fuel delivery and the ECM couldn't offset to compensate.

Sometimes I feel so stupid....

- - - - - - - - - - - - - - - - - - - -

Rich,

If you're reading this, you're probably laughing, but you'll be laughing even more when you get this in the mail:



------------------
Later,
Vader
------------------
"I cannot take this any more... Saying everything that I've said before..."
Adobe Acrobat Reader 4.0

 

*whines jealously*
I want lotsa cars too

 

Glad to see you've found the problem!

What sort of head mods have you done to it? I would like to get a little more out of my 2.5 daily driver.



------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!

 

Cool, glad to hear you got it fixed.



------------------
ASE Mechanic/Machinist/Smog Tech

1999 NBM Trans Am
1986 Chevy 3/4 ton pick up
1981 corvette
1995 Kawi ZX6R

GO #3

 

JP,

I installed a slightly better than stock 252H cam with freshened valves. The head was ported and "unswirled" (removed the swirl-port ramps in the valve bowl areas) and intake was machined open to match. Exhaust ports were opened to the manifold sizes, clutch was changed to a tighter pressure plate, the "EFE" insert in the TBI base was removed, fuel pressure raised to 19 PSIG, and the base timing is at 12° BTC.



All this because the clutch went on me again, and the engine has to come out anyway, sooo.... Since teh flatt tappet cams with the 1.75:1 rockers tend to wear the lobes quickly, I decided to install a little extra lobe. Putting a "performance" cam in a four cylinder is a little "rice-ish" so I felt a little awkward spending the time/money, but I needed to do something with my free time.

The annoying part is that I have the POS M19 transaxle (4.10 final drive) and I run at high RPMs down the road. I'd really like to find a used-but-nice Getrag 5 speeder.

------------------
Later,
Vader
------------------
"I cannot take this any more... Saying everything that I've said before..."
Adobe Acrobat Reader 4.0

 

I would be pretty hard pressed to pull that thing down, but if I have to for some other reason (I had better not have to!) I now have a couple ideas to try. I can't do much on the cam, becuase I have the roller cam, and don't know if anyone makes a replacement. I would just like to be able to keep up with traffic! (Although with my lead foot, I get ahead of normal traffic anyway)

Thanks for the pics. They give me a better idea of what to do!

By the way....Is there anything you do that you don't take pics of? I sure wish I would get myself to utilize my digital camera more!

------------------
Working on:
'84 Z28 LG4 305
Added dual elec fans.
145 MPH IROC Speedo
Building 430 HP 350
using primarily GMPP parts.
Block is in shop!

Awaiting results from all 8 ASE tests.

Starting to look like the Kicker poster child!