i just bought a fiero....

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cypherbane139

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this is my first post, i think.. so hello;)

i picked up an 87 gt that would start up and die like a week ago. got it running after i replaced the ignition components, but wouldnt idle. also after i revved it past 5k, it popped the oil filter gasket, and poured oil all over my back cat, lol

needless to say the car billowed smoke for a good 5 mins, while i scramble to make sure i didnt throw a rod.. or something. i flushed and replaced the oil, egr (which looked like it was from a junkyard) tps, map, and the IAC. it ran great! holy crap, it sounded good. and then the timing chain slipped... DOH. >_<

i met with the guy who built it, who claimed that the car had a 12:1 setup with stainless valves and everything. told me it ate timing chains, also said he was shooting nos through the egr opening... >_>

the chain and it's tensioner are destroyed, and i have a comp double roller coming in in a few days. i guess my question is, do you guys think they guy is full of it? why would you do all that to a motor and slap a cheap-o chain on it? and why the hell would you shoot nos through the egr, supposedly the car was set up to look stock, but is that safe? lol
 
Shooting NOS thru the EGR tube is not correct way of doing it. Although if he used a dry kit it would work as long as he compensated by using larger injectors and some reprogramming.

The snapping of timing chains could be high compression or it could be other issues like a bad/damaged crank, cam, or bearings from running NOS.
 
how do you run a 12:1 engine on pump gas? It would ping like crazy. At that level of compression you have to run a minimum of 100 octane.
 
i slapped some 97 with a bottle of that 108 octane in the tank the first day because i thought it just had "bad" gas in it.

also the bearings are good, no knocking or pinging, atleast before the chain jumped lol =)
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Oreif said:
Shooting NOS thru the EGR tube is not correct way of doing it. Although if he used a dry kit it would work as long as he compensated by using larger injectors and some reprogramming.

The snapping of timing chains could be high compression or it could be other issues like a bad/damaged crank, cam, or bearings from running NOS.
Click to expand...

he told me he reprogrammed the prom himself
 
well i got my chain in today, and if it isnt raining tomorrow, im going to slap it in.

Im going to try to get the specs on the cam, to see if it would he benificial to advance/retard the timing a bit, after all i have +/- 4% ^^
 
When you install the new chain, Make sure the chain guide is still there. It's a plastic/nylon wedge that mounts just under the cam gear and it is adjustable to keep the chain tight. If it's missing, This could also be another reason they have been breaking.
 
there is this metal braket under the cam, summit wasnt sure if i would need one when using the double roller, but i'm picking one up at work before i install just in case. its like 10 bucks sans my discount. (i love working at kragens XD) after its running i'll try and pop up a video/ pics of the car. at first i thought it just had some loud ass piping, but now i know better.

speaking of which, i was wondering where i could find quieter mufflers. I am not a big fan of making myself known, especially in a "sports" car. could i take something that belongs on a mercedes or something to help combat the decibles?
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my fiero flooded...

i got to the car, to find out that the rain had flooded the lot it was sitting in, water up the windows >_>

lol...

all the new sensors and solenoids i bought were under water for 8+ hours...

well the car is definatly cleaner than it was before... xD
 
... this will sound stupid, but the marks on the2.8 v6 timing chain both point up right?
 
ok.. i fixed the timing issue, the crankshaft mark was different than the stock chain. so with that fixed, it stays the same. it will sit there and idle, but if you hit the gas she goes to die. letting off brings it back up to idle. the fuel pressure stays around 38 psi. im at the end of my ropes with this thing. replaced the distributor, cap, rotor, plugs, injectors, pcv, air, and oil elements etc, waterpump, egr, tps, IAC,MAP sensor. cleaned throttle body. I found the vaccum lines melted where they contacted the second intake plenum, but even with all those lines bad, it should still be able to rev up correct? is this a computer issue, or something else? any input would be greatly appreceated,

thanks for reading :D


Edit: when i start it up with everything connected, it will start up and die in about a sec. with the TPS disconected, it will idle great, but when you hit the gas it goes to die. (come to think of it, i never got it to die all the way, it was more like a 'dead spot' like it wanted to die, and when i let off it goes back to idle). could it be because the MAP sensor isnt getting vaccum, and the ECM has no way to know that i'm trying to rev up with the TPS disconected?"
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If the vacuum lines going through the middle intake section are bad, It might not run very well. There is a vacuum line that runs to the fuel pressure regulator to set the fuel pressure level based on the vacuum of the engine. Off idle the fuel pressure should increase slightly because the vacuum will increase slightly.

The MAP and TPS sensors work together. So if the vacuum is too low (from a leak) the computer uses the input from the TPS. If the computer doesn't get a reading from the TPS Like when you disconnect it) and the vacuum is low, It will run at a default value which is a slightly richer condition.

At idle what is the ignition timing set at? It should be at 10* BTDC. If it is too far advanced, it could cause the same issue. When it idles, What RPM is it idling at?
 
ok, i've replaced the vaccum lines, to no avail. although it looks pretty spiffy. i havent checked voltage, but it seems like the TPS and MAP sensor isn't sending signals to the ECM, i havent verified with a volt meter yet, but i'll do that tomorrow. they are new, so it shouldnt be the sensors themselves. could be the wiring to the computer tho, which scares me lol any ideas?

edit: the timing was spot on, not bad ey? no light, just my ear =P

if i get good voltage readings for the map, and the TPS, the computer has to be malfunctioning correct? supposedly this thing has a reprogrammed prom. is it easy to swap them out? i'm grabbing a code reader, a DMM, and some wires tomorrow and checking everything. where can i find out which pins to the computer are for which sensor? it would make it much easier to check the wiring
 
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If the PROM has been change or reprogrammed, It could be that the mods to the engine need to be remapped. Sinister Performance ( www.gmtuners.com ) can assist you with this. Swapping the PROM is very easy to do. They can have help you get a log of what the engine is doing then you Email it to them. They then program a PROM and you should be good to go.

Don't always assume a new sensor is good unless it's a AC Delco. Many have had issues with getting bad sensors from auto parts stores.

Also check the ground wires for the ECM. If dirty, corroded, or broken, They can cause lots of non-reading issues.
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well i checked both TPS and MAP sensors, they checked out. also the wires to the ECM, both common ground and 5 volt were good, as well as the signal wires for both sensors. i'll pull the codes in a few.
 
success!!

well, i pulled the codes, er code. 51... lol so i check the two grounds on the harness to the ECM. d6 had some resistance, which slowly went up then shot to open. i fiddled with it, checked again, and it still stayed open. looked like the ECM was replaced, along with the connectors. they were done well, soldered, and shrink wrapped. but the D6 wire looked slightly burnt! i took some speaker wire i had, and tied into it to a ground i found.

she starts up, idle goes up initially to like 12-15 but drops to around 1k. just purrs. she has some hesitation, but will rev up fine, after around 2k the hesitation is gone. i figure i'll check the voltage at the TPS and adjust it so it hits properly. its .5- 5 volts right? or .45-4.5... something like that. also i am going to start searching for a good wiring routing diagram, to see what else ties into this ground. it goes into the engine bay, and then i loose it.

i could technically drive it around if i slapped tires on it =D

thanks for all your help, having someone to bounce ideas off of has always helped me in the past, but lately i have'nt found anyone around here that knows much about these things. your input was invaluble =)
 
Don't get too involved is trying to sort out some minor low rpm hesitation until you drive it. The ECM resets the IAC when the vehicle is traveling at +40mph. The ECM also features a "Block Learn" mode. Now that it is running (congrats!) disconnect the battery for 10 minutes to reset the block learn mode. Then toss on some tires and drive it around the area. The block learn will make minor adjustments to fuel and timing and store those in the ECM so it will run the same all the time.

If it still has hesitation, then see what might be out of adjustment.
 
alrighty, i will. i get a day off thursday, so some new tires, and i'll put a new clutch on order, since i'll be burning up this one ;) thanks for all your help man!

i was getting ready to punch the car, but with ur help it remains dent free =D

on a non related note, ive been checking out these wide body / chop tops.. whats your opinion on them?
 
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