Hello everyone I am new here and I'm having serious engine problems. I have an 88 firebird formula 5.0 tbi and this past month has been hell because of my mistake deciding to change my intake manifold for the first time ALONE. So my story starts here.....


I received my edelbrock intake manifold #3704 and was very excited i instantly decided I was to change it. Now so I took of the whole bit throttle body, distributor and the manifold itself no problem at all, but then this is were it went bad. I was placing my manifold on no problem at all swapped the distributor and then bolted on my throttle body. Now as I was reconnecting my fuel lines one of them ripped! So I had no reason to even try to start my engine. Next day I go to pick n pull n replace my ripped fuel line. Ok so now I'm good time to fire it up n time this bad boy. Crank it over nothing jus keeps trying and trying. So I slap the timing light on #1 plug have my dad try to crank it and I'm getting no spark!!! So I have no spark and due to money issues I decided it would be smarter to bring it to a shop and have them test my distributor ect. While it's there the mechanic notices that the fuel injector pod were the fuel line connects in was cracked and leaking. So next day while my car is in shop i go to pick n pull again n grab a throttle body of a 90 rs camaro. I go back down to shop slap tb on and he tells me my magnetic pick up n the distributor went bad. Ordered a new one slapped it in and now I'm really ready! Crank that sucker over idled pretty good timed it at 0degrees (stock) and then all off a sudden it starts spurring and dieing out. So not wanting my bill to rack up any further I take it out of the shop. Barley make it home with it idling very rough and the gas pedal actually feeling gutless like it has no power. So I get it hme and kept it running because it sounded better I go inside for about 5 10min n then cme back out and my engine is over heating and seconds later my radiator blows. So now I can't do anything. Next day I find my self in a coolant shop getting the radiator replaced. So I cme back into the shop and they say that the thermostat wasn't opening up at all and right now it doesn't even have one in it jus letting it flow. So now I get my car back to my house now time to check things.

So now here's were I'm at . My engine does this....
I kick it over sme times it sounds fine in the begining. I can hear a loud squealing coming from this replaced throttle body could be throttle blades? Bt sme times I start it and it fires up and then dies. Now just a day ago I started it up on a warm sunny day ( been raining lately) and jus decided not to give it any gas at all jus let it try. Started it up sounded good idled at 1000rpm for about 10seconds then rpms started decreasing until engine started to sputter but then it kicked back up to 800rpms and sputtered again. It did this several times until on the last sputter it kicked up to 1000rpms and stayed idling there for about 20-30mins! I dnt know how or y it did this but it did. So then I tried giving it a little gas and it would rev up but then wen winding down it would sputter but then go back to 1000rpms n stayed there. So then this morning I tried doing it but was having very hard time starting engine because it was cold.......

Here are my questions

could this be from a poor intake job? If so how did it stay at a perfect idle for 30mins?

Could this be from the used throttle body?(maybe worn shaft, bad sensors ,ect) remember there is a squeling sound coming from my throttle body

could some how I have fried electrical things from removing the intake manifold or replacing it? ( once again for some reason my thermostat wasn't opening up, what controls that? Also now my windshield wipers don't work at all and they did before perfectly fine.)

please I am in deep trouble for attempting this job with n help and I need yours!! Help your fellow 3rd gen driver! Any info or opinions are greatly appreciated. Thanks!

 

Welcome to TGO

I hope that we can find a way out of your problems.

1. - you need to reset your IAC. Since you swapped TB's ECM has no clue where IAC pentacle is positioned. There is a sticky in technical articles how to do that and it is very easy. Also check and see if you have any codes set - read a sticky how to do that (hint Pin A & B of ALDL shorted with paper clip).

2. Verify that TPS is functioning correctly. You may have a bad TPS or there is also a possibility that '90 TPS has a different pinout vs. your 88 even though the two look identical. This check is also very simple if you have a DVM and it does not require engine running, just ignition is in RUN position. At idle throttle position, TPS Pin B (dark blue wire) should read about 0.6 Volts DC - this requires back probing TPS harness connector which could be tricky! As you move throttle from idle to WOT voltage should increase to 4.2-4.8Vdc. There should not be any sudden jumps in this voltage (it should vary nicely with throttle change).

3. TPS - a lot of post intake swaps problems can be caused by flaky or damaged TPS. TPS should be mounted close to thermostat housing - similarly to OE location. TPS is thermistor and can be checked by measuring its resistance by disconnecting harness and using DVM to measure resistance across contacts at room temperature (25C) it should read around 2700 Ohms and hot (85C) 280 Ohms.

Post your findings

//RF

 

I believe RF Master Meant CTS (coolant temperature sensor) for #3, since he referrenced TPS twice and commented on engine temperature in #3.

 

Thank you - fingers were moving faster than my mind! Yes, it should be CTS (coolant temperature sensor).

//RF

 

Quick questions where is iac, tps located? What is a dvm and
how much do they cost? What is back probing the harness? And for CTS what is ohm? And what do u mean by codes set? And how do I check them

 

Oh boy - this is going to be painful. I think you need to park your car and do a lot of reading.

DVM = Digital multi Volt Meter. Allows you measure voltage, current and resistance in electrical circuit. Any autoparts store will carry a basic model good enough for your purpose for about $10.

IAC - Idle Air Controller - electronic stepper motor used to control amount of idle air.
TPS - Throttle Position Sensor - variable resistor coupled to the throttle shaft.
IAC and TPS are both bolted on passenger side of the TB.

CTS - Coolant Temperature Sensor - tells ECM (Electronic Control Module aka fuel injection manager) what is engine coolant temperature. Usually it is mounted left of the thermostat housing into intake manifold water jacket.

Ohm - a unit of resistance in electric circuit named after a 19th century German physicist Georg Simon Ohm.Think of electrical resistance as trying to pull water through a pipe. The smaller the diameter the more difficult it is draw water the pipe - higher resistance.

Backporbing - a technique used to make electrical contact with DVM test leads through back side of the connector with connector contacts. This allows voltage measurements in a fully functioning circuit. Not to be attempted by a novice (i.e. this an expert level technique)

Go read technical articles - as you have a lot to learn. Sorry to be so brutal, but it will be best for your wallet.

//RF

 

No worries at all bt one more quick question. What about the codes you were talking about?

 

http://www.troublecodes.net/GM/

 

Ok so I have be unable to find a sticky on iac reseting Nd not been able to buy a dvm yet bt I have made sme kind of progress. Ok soive noticed that when I start my car a couple times and then about the fourth time I start it up instantly i reved my engine to 2000 or so and then kept it there for about 2030 seconds and then I let it go it kinda sputter at 500rpms n then warms up to about 1000rpms! I then let it idle for 5-10minutes n reved it a bit n it would return to 1200rpms n stay there. So I hesitated for a minute and then decided to throw it in reverse. Changed in perfectly n stayed at a 800rpm perfect idle. I backed up put it in drive and then gave it some gas and it hesitated just a little but was able to drive not bad. At higher speeds car felt fine jus hesitated off the go. If I smashed the gas it would really hesitate bad. I was able to drive around ok but was hesitated. Soo what is up with this?????

 

TPS - IAC reset procedure.
https://www.thirdgen.org/tpimod2

Do you have a timing light??

Can you take a digital photographs of your engine bay, intake etc. Doing this not seeing your engine in its current state is tough.

//RF

 

Did you disconnect your Electronic Spark Timing connector before you adjusted the timing? (you should have)