Hi there! I recently purchased a 91 sho not to long ago, and I’m having a misfire problem. Sometimes when I start the car I have no power and I could be flooring the gas, and the rpms barely climb up past 1-2k, and other times it’s fine. We replaced the cognition coil but that doesn’t seem to have fixed the problem. For whatever reason 6 is not sparking. Any ideas? Thanks!
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pull your codes to see if anything is stored
Has it been like this since you bought it? Have you tried changing the plugs and wires?
-Chad
-Chad
The plugs were changed before I bought it, and the wires are all fine.
The plug wires look pretty dusty, did the previous owner say when they were last replaced. how many miles are on the car now?
luigisho
SHO Member
I would assume nothing and start from scratch with plugs and wires and get codes. Those wires look original to me with the plastic loom and numbers unless you folks know about replacements that have this. My last few aftermarket replacement sets did not.
FastCAD
SHO Member
If you haven't owned a SHO before the codes would be the first place to look. The check engine light would flash then go out ie: the light only notifies you that a fault has been recorded. Get an OBD1 scanner there are reasonable ones available. Start there. you will need it.
Don't throw money at the SHO looking for a problem you will have plenty of time to spend $$$.
By the looks of your avatar that SHO looks pretty clean (outside) and a '91 is worth having.
For no cost check the coil wiring for correct placement. Right side back to front 1,2,3. Left side 5,6,4.
Start the engine let it warm up a few minutes. Go to the cam sensor (pass. side back corner of the intake manifold). Dis-connect the sensor if there is no change or very dirty or oily it could be faulty but this piece does throw a code so my advice is first things first. Think like the computer as your friend with no money lol and is only trying to help you learn how the Yamahammer works.
Best to ya.
keep us posted.
BaySHO Performance
SHO Member
First thing to ALWAYS do is pull the codes. Very few of them cause the Check Engine Light to come on, so don't assume there aren't any. Either use a paper clip: http://wiki.wikisho.com/wiki/EEC_Self_Test_Procedure
Or buy one of these: https://www.amazon.com/INNOVA-3145-...+ford+obd1&qid=1632161157&s=automotive&sr=1-4
The advantage of a scanner is that you don't have to disconnect the battery to clear the codes as you would have to do with a paper clip.
Or buy one of these: https://www.amazon.com/INNOVA-3145-...+ford+obd1&qid=1632161157&s=automotive&sr=1-4
The advantage of a scanner is that you don't have to disconnect the battery to clear the codes as you would have to do with a paper clip.
FastCAD
SHO Member
When you are doing a KOER self test you can pull the paper clip just at the point where the PCM tests each cylinder and that will erase all the stored codes.
BaySHO Performance
SHO Member
But first when you pull codes, do the KOEO.
CastorTroyN7
New Member
I'm new to the Ecoboost SHO world, but have a ton of wrench time on the 1st Gen SHO's.
First, those plug wires look old, the previous owners may have replaced the plugs, but unless they used a set of cables from a junk yard find, there's no way they replaced them.
This is going to be a really dumb question, but what steps have you already taken to determine that #6 isn't firing, and is the problem?
When you have a no power situation, does the motor all of sudden come alive around 3,700 RPM?
Josh.berding7689
New Member
Pull the plug wire from cylinder 6, if the engine starts to idle rough it's good.
if you do have one cylinder not working the other one shouldn't be either (the ICM / DIS fires the cylinders in pairs) so cylinder 2/6 are a pair, as it 3/4 and 1/5. if it'ss a coil pack issue, one goes another goes. figure that out then update please.
if you do have one cylinder not working the other one shouldn't be either (the ICM / DIS fires the cylinders in pairs) so cylinder 2/6 are a pair, as it 3/4 and 1/5. if it'ss a coil pack issue, one goes another goes. figure that out then update please.
