So you may have been reading about how my car goes crazy with AFR's and idles high, well I think I may have found the problem and this might help others. I thought the high idle was caused by a vacuum leak around the injectors because my vac/ boost gauge reads correctly, but the engine runs lean. As I previously mentioned, I had put new injector "isolators" in there. These are the little black washers that slip around the injector stem, and seal the injector to the intake manifold. The Miata part number is 13-257. I remember these not fitting perfectly snug on my injectors (RX-7 460's PN-195500-2010.) I called the Mazda dealer and they looked up the Miata part number, and then I told them I swapped my Miata injectors with RX-7's and are these isolators the same? They told me "No" and gave me this part number N350-13-257. I'm like 13-257? that's the same number. The guy said it's a reference that the computer uses to identify this as the "isolator" and that the RX-7 part is different than the Miata part. I didn't really believe him so I asked the price and he said $2.75 I think, the Miata ones were $3.90. So if the price is different, than the part must be different. I am picking these up on Friday, and I'm putting these in right away. I think this may very well be the root of all my AFR craziness, at least I am crossing my fingers...

 

Spray some Brakleen around each of the injectors individually. If the motor does something odd, then its the injector not seating right. If it doesn't do anything then your injectors are sitting fine. The brakleen is great for identifying vacuum leaks.

 

large gobs of RTV goes a long way too :P


brake cleaner (highly flammable stuff is key) works wonders to find leaks.

 

I'm pretty sure they are seated right, I'm certain it's just incorrect seals. I guess I'll find out friday when I get em and throw em in.

 

I went through that when I swapped to RX-7 injectors. I had my original isolators RTVed in place and ad to swap them out 'cause the RX-7 injectors wouldn't fit. Had to use the RX-7 ones. Same OD as ours, but the ID is larger.
--Alex

 

When I put the miata isolators on the RX-7 injectors, they felt sloppy like they weren't near as tight as when they were on the stock miata injectors. If this fixes the problem and my car runs great, and my AFR's run smooth, I'll take back everything bad I ever said about MS. My friend's dad is in business with Bowling and Grippo and he actually told me about MS before I even was a member of this web site. He said that your engine has to be pretty much in perfect running order for the MS to work, just like any other ECU. He told me if the engine isn't up to par, I'll never get it to run right off of the MS and this is why a lot of people claim MS and EMS-Pro to be garbage. When in retrospect, it's simply a machanical flaw, or the user themselves.

 

Might be a silly question, but are you running the MS in parallel or are you actually piggybacking it? Does the stock ecu control any fuel or did you totally cut that wire in order for the MS to control it?

 

In parallel. The stock ECU has no control over spark or fuel.

 

So I picked up my RX-7 insulators today, threw em on, started the car up, and same thing. Actually it seemed to idle a little lower, like 1300 RPM. The miata insulators had like a taper on them, while the RX-7 ones were just like fat washers with no tapers. They slipped over the pintle caps and onto the injector stems and felt like the same ID as the Miata ones, which fit loosely around the stems. When I pushed the injectors into the intake and put the rail on, the rail seemed to fit tighter like it was putting more pressure on the injectors. I attached a log and my .msq again. I drove it for like 20 minutes or more and I got 2 resets very close together. I did not have ECO correction turned on, but I did have overrun turned on. If I start the car when it's hot (heat soaked) it idles high and AFR is really lean. If I drive it awile and come to a stop sign, it'll idle high and AFR's are really rich. Possibly a Coolant-Related Air Density issue?
loaded.msq

log1.xls

 

That little pop that happens when I turn the key on sometimes...
The other night it blew off my boost gauge line. Is it possible that this coulda blew out a seal or something worse to cause my high idle crap?

 

Sounds more like a heat-soaked IAT. I moved mine out of the engine bay (read: away from the radiator's heat) and no longer get those sort of issues.

 

Isn't the point of an IAT sender to measure the temperature of the air entering the engine? If it's moved to outside the engine bay, I would think it would give artificially low readings to the ECU.

 

It can be anywhere on the cold side pipe and give accurate readings. What koto is talking about is the affect that radiant heat has on the sensor after sitting when hot. The temp will be artificially hot until the motor gets running again.

 

Got it - all of my intake tubing is inside the engine bay, so I got confused.
I mounted the IAT sensor just before the throttle body, so it isn't near the radiator. I've also noticed that it doesn't heat soak much while sitting, but that could be partly due to the tubing being plastic.

 

I'd still consider just before the TB = near the radiator, that's where mine was. I am using Al pipes though.

Now the sensor is post intercooler inside of the wheel well and all is good (except for some AFR wackiness but that's another thread and not due to the IAT).

 

search "better spark output circuit"