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I know this has been covered many times but after searching the entire weekend and the only real fix is adding more ground wires or buying a PFC. Is there anything else it could be? I have a ground kit installed to the negative battery post, to the engine block and both factory ground points.
Everytime at 3000rpm coming into boost it's like a lag/hesitation and then takes off like a rocket ship. I have a knightsports tuned ecu, full 3.5" downpipe to a SARD 3.5" high flow cat and 3.5" hks cat back, Apexi intakes and ARC intercooler/hard pipes.
My boost pattern in 3rd to redline is about 14/12/14. Would love to have this fixed because in 2nd gear going around a corner and boosting it's very for the back end to start spinning. It's like dumping the clutch while taking off but in a corner because boost all of a sudden wants to come in full blast.
It's a bug in the programming of the stock ECU. You can make it *better* with grounds but it never really goes away. I've driven super clean low mileage FD's that had the 3000 RPM hesitation.
You wanna get rid of it, get a PowerFC, period. Not to mention the PFC gives you a lot more headroom and flexibility for down the road.
3K RPM Light-throttle hesitation - One last ground
After adding several additional grounds that had been recommended, I never totally got rid of the 3K RPM hesitation, and it was getting more annoying over the past year or 2. Last week I added one more ground. This one (~6-gauge with a lug on each end) is from the battery negative to the front upper crossmember - the LH-most 10-mm screw on the aluminum piece.
Today we went for a ride, and for the first time that I can remember in the last 15 years, there was absolutely no 3K hesitation. So this new one seems to have made a difference.
As inferred in the "Improving grounds and voltage buffering" thread ( https://www.rx7club.com/3rd-generati...ering-1133760/ ), it seems that there may be a VERY high threshold level of ground conductivity (the inverse of resistance) necessary to get everything controlled by the FD3 OE ECU (or any other ECU) to operate correctly. So I don't think there was anything magical about the particular ground I added (above). I think I just reached a level of ground conductivity (to the chassis, etc.) that made the 3K RPM hesitation disappear. If it recurs, I will add more ground cables to other points in the engine compartment and/or re-clean the contact points of the current ones to see if that helps.
This, IMO, reaffirms the need for excellent ground conductivity between all relevant points as has been stated in many previous threads.
In keeping with my conclusions in post # 5, I added another ~6-ga ground (the thick black wire) to supplement the OE one from the engine hoist bracket to the firewall. The black gunk on the firewall is liquid insulation paint. I have not yet driven the car with this. The weather is not cooperating. Photos attached. rear ground 1 rear ground 2
Went for a drive for the 1st time since I added that last ground (above). I did all the things that provoked it previously - gentle throttle application in several gears from ~2600 to 3400 RPM. Again, there was no 3K RPM hesitation. This is the best it's driven in many years now that I added these 2 ground cables. I had gotten used to avoiding passing through ~3K RPM at light throttle to avoid it. Now I don't have to.
The ground you added from the UIM to firewall is similar to the newer version of that ground strap that Mazda made. They revised the part number at some point.
The stock ground strap has a black push-to-disconnect that connects to the firewall. I think the amount of surface in that connector is pretty small, hence the revision.
The ground you added from the UIM to firewall is similar to the newer version of that ground strap that Mazda made. They revised the part number at some point.
The stock ground strap has a black push-to-disconnect that connects to the firewall. I think the amount of surface in that connector is pretty small, hence the revision.
Dale
The one I added last week was the large black cable. The copper one, which really didn't help, was one I had left over from another project that I substituted for the OE one many years back.
Yeah, I don't think you can even get the old one any more. If you get the part the only thing available is the updated design. Regardless Ray can make sure you get the right one.
With the extra ground cables I mentioned adding in this thread, we took a 30+ mile drive today (~70F ambient). Local roads, lots of transitions through 3K-RPM. No signs of the 3K-RPM hesitation. So far so good.
the current number is FD01-67-E70A,however its NLA.
the good news is that its just a piece of braided wire with a 6mm and 8mm eyelet on the ends, very simple
Thanks, but I was asking about the UIM to firewall ground. It has a spade connection at the firewall. Mine has been on and off and twisted up over the years and looks it’s age. OCD kicks in every time I look at it.
Maybe you’re referring to the exhaust ground strap? That one looks raggedy on my car too and something for the stock ECU guys to not forget. But with my PFC I’m not using the O2 sensor, so I’m not sure that does much on my car.
Thanks, but I was asking about the UIM to firewall ground. It has a spade connection at the firewall. Mine has been on and off and twisted up over the years and looks it’s age. OCD kicks in every time I look at it.
Maybe you’re referring to the exhaust ground strap? That one looks raggedy on my car too and something for the stock ECU guys to not forget. But with my PFC I’m not using the O2 sensor, so I’m not sure that does much on my car.
Mazda updated that ground strap to get rid of the spade connection, but both are NLA.
there are a bunch of other ground wires on the newer cars that are available and range in price from $9 to $30, its just hard to tell from the parts catalog how long it is, and what end is on it and such. basically you should go peek at a new Mazda and see if its got one thats close enough
I had very very severe 3k hesitation.
It has since resolved since my local Mazda dealer guru cleaned, replaced, and added additional grounds.
Attached is a pic of one of those. Close up
Today's drive
