I am not sure where to start I am helping my 18 year old. We did a motor swap from 2 84's 1 manual aan 1 auto trans. We took the motor out of the auto and put it into the manual. Now we can not get it to run right. With jumper I gat get it to time at 8 deg once I pull the jumper it will bounce from 2500-3000k rmps. I have cleand the egr and new gasket then got a tps code replaced that. The motor ran good befor the swap we moved all vacuum. I am out off ideas.

which computer are you using?

https://www.fiero.nl/forum/A...070315-2-078592.html

We used the manual ecu and wiring out of that car so just swaped the motor.

quote Originally posted by shortbus: ... it will bounce from 2500-3000k rmps. The motor ran good befor the swap we moved all vacuum.

Sounds like a major vacuum leak. Check all hoses and connections.

Possible junk in the fuel system got loose during the swap. Spray a little starting fluid in there and see if it smooths out.

Found 1 vac line bad/cracked replaced all then sprated with carb cleaner and the motor did not rev/speed up at all. It will idle at about 1500 with paperclip in. I do have a code 15 coolant sensor high voltage (could this cause it?
I also tried to cap the pvc and there was no change in the idle?

quote Originally posted by shortbus: It will idle at about 1500 with paperclip in.

What RPM does it idle at with correct ignition timing and the paperclip removed?

quote Originally posted by shortbus: I do have a code 15 coolant sensor high voltage (could this cause it?

If the coolant sensor is faulty and the ECM is being told the engine coolant is always cold, yes, I suspect the engine could idle higher than it should.

Thanks for all the input just swapped IAC with the one of the other car purrs at 800rpm's.
The Temp sensors had no impact on how it ran both of them made it run the same(we tried them both before and after the IAC)
But it did throw a TPM code I just put a new one in at the start of this last weekend tried the old one back in still throws a code ( I left the batt dis-connected for 1 hour in between the changes too)

quote Originally posted by shortbus: The Temp sensors had no impact on how it ran both of them made it run the same(we tried them both before and after the IAC)

Keep in mind there are two different "temp sensors" on the duke, as discussed Here. One is just for the temperature gauge, the other is for the ECM.




But hey, if your problem is solved... great!

ok guys im still having problems im getting a code 15 and a code 21 its like its running with a bad tps it doesn't like to start and runs really bad i have read some where that the coolant code 15 can mess up the fuel system is that true and if so where do i start and i know the tps is good i just got a new one but when i test it comes up as 5v when it is closed it does this with the old one and the new one also if i put the jumper in the computer before i start it then re tune it it runs good until i pull the jumper then it runs bad again also i have replaced the coolant sensor with a spare i had around

quote Originally posted by shortbus: ok guys im still having problems im getting a code 15 and a code 21 its like its running with a bad tps it doesn't like to start and runs really bad i have read some where that the coolant code 15 can mess up the fuel system is that true and if so where do i start

I addressed this in my previous post. Have you checked or replaced the coolant temp sensor for the ECM?

yes i have replaced it with a second one i had but i think i may have found the problem the one that controls the fan had broken in the swap the wires and the plastic pulled out of it i hope this will solve the problem i ordered a new one to day it will be here tomorrow around noon

quote Originally posted by shortbus: i think i may have found the problem the one that controls the fan had broken

The coolant fan switch will have ZERO effect on the trouble codes you've posted.

ok how do i trouble shoot this code then i know its not the sensor i have switched them out with two that have worked

Code 15: Infinitely High resistance means a broken or disconnected wire somewhere in the CTS circuit....assuming the CTS is good. Fix this code first.

Code 21: TPS. Most people start with a good cleaning and see what happens.

[This message has been edited by Gall757 (edited 09-19-2013).]

so i assumed the cts was good and tested the wire from the connector all the way to the computer and it was not broken so i tested the cts the two of that i had and i think they are bad in my computer room its like 80-85 degrees and the cts is saying air temp is around 120 (around 1.021 ohms) for both of the cts either i am testing the resistance wrong or they are both bad now being that i have replaced the tps would the cts problem because the tps code 21 to go off and the car to run rough? when i test the old and the new tps i get 5 volts on the black and the blue wire which would mean wot right? and for closed throttle it should be at 1.25 if i have read right in my Haynes manual

quote Originally posted by shortbus: i tested the cts the two of that i had and i think they are bad in my computer room its like 80-85 degrees and the cts is saying air temp is around 120 (around 1.021 ohms) for both of the cts either i am testing the resistance wrong or they are both bad

Stick the end of each CTS into a pot of boiling water and see what the readings are.

i assume i am reading my volt meter correctly because it it reads 1.021 which i would assume is 1021 i hope i right with that?

quote Originally posted by shortbus: so in the bolling water the one reads .490-.500 which would be 150 degrees and the other one reads .690-.700 and thats like 135 degrees so should i go ahead and replace it with a new one?

I've always used WinALDL to see what's going on (as oppposed to using an omhmeter on the sensors), but it seems to me from what you've reported that those CTS units are indeed faulty. Perhaps someone can chime in who's more familiar with the method that you're using.

quote Originally posted by shortbus: if i dont get to it will it hurt to run it with out as long as i use the max ac so i can get the fan on?

The fan normally doesn't come on until the coolant reaches the surface temperature of Venus, so I wouldn't worry about it.

But yes, you can simply turn on the A/C if you feel the fan is necessary.

ok so i ordered a new cts and sense i blew up the fan switch i tried to get a new one for the one with ac but no one has one that my local part store can find so i got the non ac one and i will have to figurer out how to make it work all of the parts will be here tomorrow so i will up date more probably tomorrow or Saturday when i have time to get the parts in im so hopping this all works i i miss my fiero so much

so i put the new cts in and it made little change at all it still doesn't like to start you have to put gas down in the "carb" from cold start and starts ok from warm but it still putts every once in a while could this be a problem with the new cts or maybe even the computer? and the codes are still there i even disconnected the batt for like 20 min just to make sure all the juice was gone

quote Originally posted by shortbus: so i put the new cts in and it made little change at all it still doesn't like to start you have to put gas down in the "carb" from cold start and starts ok from warm...

So this engine supposedly ran fine in the other Fiero? So what's different now? No doubt the fuel, gas tank, fuel pump and fuel filter are different.

How old is the gas?

How much fuel in the tank?

What's your fuel pressure like?

When's the last time the fuel filter was replaced?

quote Originally posted by shortbus: ...and the codes are still there i even disconnected the batt for like 20 min just to make sure all the juice was gone

Did you actually completely disconnect the battery?

I find it difficult to believe that the ECM has somehow been able to retain the codes with NO power.

i did disconnect it all the way and the car when i started the swap had two year old gas with half a tank so i went out and got two bottles of octane boost and 5 gallons of fresh 89 octane well in running it and cleaning the injector and not seeing the gasket was broke i went threw another 1/4 tank then i filled it with another three gall of 89 octane and the fuel filter is off the one that was running but the pump and all that have been sitting for a while do you thing bad gas or some thing like this could cause the code 15 because originally i was thinking it was bad gas making it do this but then i looked in to the code 15 more so i disregarded the bad gas

quote Originally posted by shortbus: i did disconnect it all the way and the car when i started the swap had two year old gas with half a tank so i went out and got two bottles of octane boost and 5 gallons of fresh 89 octane well in running it and cleaning the injector and not seeing the gasket was broke i went threw another 1/4 tank then i filled it with another three gall of 89 octane and the fuel filter is off the one that was running but the pump and all that have been sitting for a while do you thing bad gas or some thing like this could cause the code 15 because originally i was thinking it was bad gas making it do this but then i looked in to the code 15 more so i disregarded the bad gas

Your posts would be a whole lot easier to read if you made use of a period (.) between sentences.

quote Originally posted by shortbus: so i assumed the cts was good and tested the wire from the connector all the way to the computer and it was not broken so i tested the cts the two of that i had and i think they are bad in my computer room its like 80-85 degrees and the cts is saying air temp is around 120 (around 1.021 ohms) for both of the cts either i am testing the resistance wrong or they are both bad now being that i have replaced the tps would the cts problem because the tps code 21 to go off and the car to run rough? when i test the old and the new tps i get 5 volts on the black and the blue wire which would mean wot right? and for closed throttle it should be at 1.25 if i have read right in my Haynes manual

You should be getting about 4.5 volts WOT and .5 to .75v closed throttle. Sounds like the black wire has a high resistance problem.



So according to this schematic the TPS and the CTS share the same return (isolated ground) wire to the ECM. That's where I would be looking first. Either a corroded terminal /broken wire in the ECM connector or a high resistance joint where the two wires connect in the harness.

C1 (Blue/Black connector) Pin 11 - Black wire

[This message has been edited by phonedawgz (edited 09-22-2013).]

so with the beep setting on my multimeter i have found that the black common ground wire is good and they do go all the way to the computer. also in testing the tps voltage today i had it disconnected to see if the value would change to make sure there is nothing wrong with the wiring and with the tps not plugged in the reading was .05 on the blue (middle wire) but when it is plugged in i get 5 volts across all three wires. i also tested the resistance of the brand new cts the multimeter read 1.1xx so from the cart that i have found on-line it would be about 120 Fahrenheit and this was with the motor not running at all to day so the coolant was around out side temp of about 70-75. so could it possible be that i still have a faulty cts, or maybe the common ground is not getting in to the computer (i know it gets there but i don't know if it makes it inside of the computer)? also could a possible faulty tps make the cts act incorrectly? i ran it a little bit today and it started a whole lot better (did not need to put gas in the carb) and it wasn't popping like it was before when i ran it.

My two cents, I would have chucked the gas from the get go. I just bought a 86 with hardly any gas that was sitting around for a couple of years, put new gas in it and I had a hard time of missing, lack of power, smelly and black smoke for about 30+klms. The car is a whole lot better now, but I will clean the tank, new filter and new gas next spring as it will be parked for the winter.

Bad gas/moisture can sure cause a lot of trouble!!!

quote Originally posted by newfiejeff: Bad gas/moisture can sure cause a lot of trouble!!!

My experience with at least three Fieros that sat for years is that old gas is fine... just add some fresh gas to the tank.

However, water in the gas tank is not fine.