ECM Jumper / Ignition Timing (Page 1/1)
fgt1988 APR 15, 05:45 PM
This is an an odd situation but thought Id ask in case anyone knows or seen this behavior before - Looping the ECM A & B pinouts with a clip and all fine and can read diagnostic codes but if you try to start the car for ignition timing purpose, it will not fire up until you pull the paper clip out -

So as far as timing the car with jumping the ECM that s a no no on this 88 GT 5 Spd .. Anyone have a clue what would prevent that ? -
Patrick APR 15, 08:44 PM
With the jumper in place, the ignition timing is temporarily retarded. If the engine won't start with the jumper in place, I'd say the timing has been set with possibly not enough advance. Keep note of where the distributor is currently located/pointing, loosen the hold-down bolt, and turn the distributor a bit counter-clockwise. This will advance the timing, and hopefully allow you to start the engine.

However, you're not out of the woods. You should try to find out why it's been timed improperly. There's a chance, and it's not uncommon with old/original components, that the outer ring of your harmonic balancer has spun on the inner hub... thus rendering it useless for correctly timing the ignition. You need to determine that TDC for piston #1 still lines up the wider groove on the balancer with 0° on the scale. If it doesn't line up, you need a replacement balancer.

How well was the engine running? Did it appear to be lacking power?

[This message has been edited by Patrick (edited 04-15-2020).]

fgt1988 APR 16, 09:33 AM
Well the balancer only has a few hundred miles and engine has about 40+K so I know it is not related to any faulty parts that I know of right now - Engine idles fine and it s more of just tuning it back to normal - I had done some clean up and removed the distributor and got it back to TDC#1 and wanted to be exact on the timing -

I will try to advance it and see if it will fire up with the ECM looped -- I ll come back with results soon ----- with all of the quarantining going on, figured i ll make time to catch up - the car sits pretty much year around - Thanks a bunch for the provided details -

MulletproofMonk APR 16, 09:55 AM
Are you using the stock Fiero 2.8L or is it upgraded to the 93-95 3.4L? If it is upgraded to the 3.4L swap, you need to swap over the 2.8L harmonic balancer. If you don't, the timing notches from the 3.4L harmonic balancer won't let you time the car since the timing marks are different. My friend found this out the hard way trying to fight a timing issue...

------------------
-Brian

My 87 GT Poly Suspension Upgrade (all pics) thread
Removing the roof panel
My HUD install thread
Modified stock air canister and base to 3.5 inch for 3800na

fgt1988 APR 16, 10:34 AM
yes it is 3.4 engine and the harmonic is the 2.8 OEM bought from the Dr Harmonic out on the west coast - I do have an aftermarket 3.4 harmonic notched for 2.8 timing mark but decided not to use it and it is fairly new with some dust but sitting on the shelf - Appreciate your help -
Patrick APR 16, 03:49 PM

quote
Originally posted by fgt1988:

I had done some clean up and removed the distributor and got it back to TDC#1 and wanted to be exact on the timing.



Would've been helpful to have mentioned that earlier.


quote
Originally posted by Patrick:

You should try to find out why it's been timed improperly.


fgt1988 APR 20, 09:34 AM
As promised I d come back with results ------ I went ahead and advanced the timing a few degrees and looped the ECM and sure enough, she fires up - I was able to get the timing right where I want it but have not driven the car yet for a good test -- If no rain this upcoming weekend, I ll take her out for a spin - Thanks to everyone for your assistance and support - Be safe and continue self distancing ---