Hi,

I don't really think this is a problem but I am very curious as to why it is doing this. According to my cluster, sometimes the motor cuts-off at 6800rpms and sometimes 7500rpms.
For example, if I start my car in the morning and go to work, when I get on the highway and floor it, it usually cuts-off at 6800rpms the first time, but if I floor it again it will go all the way to 7500rpms. And I know it's not the cluster acting up since I hear the sound difference between the two cut-off points. But it doesn't happen all the time.

Also, sometimes the motor revs smooths until 6800rpms, then has a slight hickup at 6800rpms like if the ecu cuts the fuel only once, then it will rev until 7500rpms. Strange no?

If it makes a difference it's actually a sohc zc, similar to d16a6, on stock 91 Si ecu.

Thanks

 

Are you railing on it before it is even warmed up to operating temp?

 

No I never do that. There is about 5km/10 mins drive before I get on the highway.

 

I looked up the specs for a D16A6 and the zc the fuel cut is 7300 you'r not even supposed to take it up to 7200 let alone 7500...

 

Like I mentioned in my post if you read correctly, this is by looking at the cluster which we all know is inacurate at those high rpms. Besides that's not the point, the point it rev limits at both rpms at different times and I am curious to why?

And why am I "not supposed" to rev it to 7200rpms? My best and most consistant times on the track have been made shifting first to second at 7200 rpms, second to third at 6900 rpms, and that is with over 200 passes made last summer. I know the a6 starts loosing power at around 6600rpms according to dynos but because of gear ratios I get my best times shifting at the rpms above. And again, no I don't beat on my car until it has reached operating temp...now back to the original question...

 

I don't have D-series experience but i experienced something like that twice on my B18C running OBD0. 1.Ignition module 2.Thermostat Housing Ground But it was much more violent that a Hickup, it was like an actuall Rev Limiter.

 

Thanks for the input. It's hard to describe, sometimes it really rev limits at 6800rpms, like an actual rev-limiter. Sometimes it can rev-limit once or 2-3 times at 6800rpms then go to 7500rpms...I have noticed it does that especially when I reset my ecu after having iacv problems, kind of like if the ecu "learns". Oh well.

 

Could be parts in the dizzy wearing out. The ECU get's its rpm signal from the distributor, if it's worn out the ecu won't see actual rpm and the rev limit will do just as yours is.

 

Good point, still debating on going with a b16a (already have the motor only) or putting on my y8 manifold and ported head I have laying around and going obd1. Either should solve this issue.

 

My money would be on the Ignition Module. you can find it really cheap i think Mobiletron makes them, get a new cap/rotor and it should be fine. It shouldnt cost you more that 50-60$

 

most likely its the dizzy, borrow a friend dizzy and try it if not just buy a new one. Should fix your problem.

 

well my tachometer is inconsistent, my car was tune on s300 to rev to 8,000rpm but when i floor it down, the tachometer only shows that it revs only to 7,000rpm (that sucks when u want to see it go all the way down there!! -_- )

 

Thanks everyone for the input, good to know, I will most likely go with an obd1 conversion either with my b16 swap or for my D build which should solve the problem.