pszikla

Strange problem noticed yesterday.
Was out for a drive on a nice sunday afternoon and found myself on a looong straight country road with zero cars in site so decided to open it up a bit.
Hits redline easily in first and second but then from third on it gets to around 6200 rpm and then struggles to increase in rpm's and feels like it is hitting a rev limiter point/fuel cut-off point.
Shifting up it accelerates well again to that approx. 6200 rpm and then struggles for any more RPM.
No other symptoms, idles well, pulls well.
I had one of the original GIAC flashes many years ago and wonder if it has somehow deteriorated with the years and needs an updating.
Any thoughts?
Pete

Ubermensch

Possibly something as simple as tired spark plugs (or coilpacks). Higher gearing=>greater load on the engine. Weak plugs can have difficulty igniting the mixture.

Were there any recorded misfires?

pszikla

good thought!
I'll check the codes tonight!

pszikla

pulled stored codes and got
P1124
P1126
both are oxygen sensing range 1 and each code is for 1 bank of cylinders.
Not sure if this relates in any way to my issue.
I am starting to lean towards old plugs since it has been a while since I changed them.

Also P0446 but that is charcoal filter related so am discounting that.

Ubermensch

Incomplete combustion (bad plugs or coils) will send partially burned fuel through the exhaust and potentially cause strange oxygen sensor readings. I'd inspect the coilpacks while doing the plugs. I ended up having to replace all of mine at 60k miles, but they've been good for the next 60k.

S.

Macster

I'm with ubermensch. Tired spark plugs.

Replace the plugs. Form a habit of noting which plug comes from which cylinder and note the condition/color of each plug.

Then worry about the p1124/P1126 and P0446 codes afterwards. They suggest something at least one something is going on and there may be two somethings going on besides the failure to reach redline.

Before I tested the plugs by redlining the engine I'd sort out the reasons for the error codes.

pszikla

I think that for the cost I am going to change the plugs and coilpacks.
It has been long enough ago that I don't remember what the mileage was when I changed the plugs and I think the coilpacks are actually the originals now at 95K miles.

Will let everyone know results after that.
thanks for your thoughts!
Pete

alpine003

If you got a '99 based on your profile, don't forget the spark plug tubes and o-rings while you're in there.

pszikla

good point!
thank you!
{Pete