phinsn98

iTrader: (2)

History: The fuel pressure regulator went bad (it started leaking fuel) When I took it in to have the regulator replaced the primary injector on the 1st rotor locked up. I ordered two RC engineering 550cc primary injectors. At the same time I replaced the TID with the Chris Sanders aluminum TID. When I got the car back the car was running (make your eyes water), (get horrible gas mileage) RICH. In the process of all this I was also dealing with loosing anti-freeze but not on the ground. It was passing through the tail pipes. I had my mechanic tear the motor down only to find out that the coolant had corroded the coolant passages in the rotor housings to the point that it was passing into the combustion chamber. This was on a one year old Mazda reman by the way. Can anyone say fresh rebuild? In the process of all this I decided to replace the factory harness on the injection side. Everything was back together and the harness was goin in only to find out that we had the wrong harness from Mazda. When we had them cross reference the part number one more time we come to find out that they shipped us a harness for the low impedence injectors (86-87). Well guess what the harness for an 88TII with ABS is no longer made. We looked at the difference between the two harnesses and the only difference was the resistors for the low impedence injectors so we bypassed them. Well you'd think that would solve the everything. We'll here is the scoop. The car idles better then it ever did. It even runs well with the AC on. The downside is that the car has weird hesitation while cruising between 2000 and 4000rpms. It still runs stupid rich. If you step on the pedal while the car is parked, the engine breaks up between 2-4k. I know the rich lean guages are considered useless but it follows the engine to the T. When idling it's full in the red (full rich) When cruising it bounces but picks up on the slight hesitation. When stepping on the pedal slowly while the car is parked the car breaks up and the guage is all over the place. We've tried a different air flow meter at different angles, a different throttle switch, a different boost sensor and even installed a MSD 6A on the leading coil. I'm really starting to wonder if I have a grounding issue with the new harness or there is something more to the difference between the two harnesses then we originally thought. As far as the the richness is concerned I'm starting to think that the new injectors are causing the old secondary injectors to leak under pressure. I'm lost. If anyone can follow this and possibly give some good advice it would be greatly appreciated.

The goal of this new harness was to go with the K2RD plug and play Haltech. I'm not sure I want to go with it until these issues are ironed out.

late,
dave

phinsn98

iTrader: (2)

gotta bump it

WAYNE88N/A

wow... since no one else has answered, I'll give it a go; there's a ground on top of the block (rear rotor housing or so) for the injector harness- if you changed the harness I'm sure you noticed it... have you checked it out O.K.?... I also just for ***** & grins ran an extra ground from that point to the firewall when I was down in there last time- didn't really have a problem I was trying to fix, so I can't tell ya if it helped anything or not...Your problem could be something totally off-the-wall, though...good luck...

phinsn98

iTrader: (2)

That ground is intact. I'll try and make this a little simpler. If you had a car with a high impedance ECU and injectors and someone gave you a BRAND NEW harness but from a low impedence TII. How would you rewire the harness so that it worked properly?

WAYNE88N/A

The way I understood the first post of yours, you bypassed the resistors in the new harness, right? Basically what it boils down to, is you need to show the ECU the same resistances it saw from the old harness/ injector setup...If you still have the old injectors & harness, measure the resistances, & see if the setup you have now matches...Now I'm assuming the resistors we're talking about are in the harness, there's also another resistor block under the air filter box, but since I don't have this setup, I don't know much about it...

WAYNE88N/A

BTW, Kevin's got a good writeup on the different injector setups and how to interchange them on his Rotaryressurection website...

HAILERS

I'd buy me one of the solenoid resistors that I've attached a jpg of with this post and plug it in and bolt it to the chassis.
You can get them from wrecks in the junkyard or advertize for one on the for sale/wante site on this site or look around on EBay for someone who sells a lot of RX parts and email them. My spare is not for sale by the way. They are worth about fifteen to twenty bucks max.

phinsn98

iTrader: (2)

I'm not sure what that's solenoid resister is supposed to be used for. Can you be a little more discriptive of its purpose?

Thanks

phinsn98

iTrader: (2)

bump

WAYNE88N/A

I THINK it's the means of adding resistive impedance to the low impedance injectors of the pre-87 1/2 cars, so that the ECU sees approx 12 ohms per injector...Hopefully somebody can back me up on this, or call me an idiot, whichever comes first LOL...

phinsn98

iTrader: (2)

Well I've had no luck with this hesitation issue. The car is completely grounded. I've pulled the new harness out and put in the old harness. I've swapped the AFM, TPS, Water Temp Sensor, ECU, coils. I've removed the set of RC Engineering injectors and put in a stock set of high impdence 550cc injectors. I've changed plugs, wires nothing. The one piece of advice that I've recieved was from Dale Clark. He felt that it was a vacuum leak. He stated that he pressurized the intake with about 10-15psi or air and listen for a vacuum leak that you might not have been able to fine before. The o-ring on the throttle body cover was toast. We replaced that and the idle was even smoother and it was less rich. The hesitation issue is completely intermittent. Sometimes it's worse then others. I can't pin it down. Sometimes I don't feel it at all. I sware it seems like something electronic. I've yet to try injector cleaner or go over the entire car with contact cleaner. I know they say that a Haltech will get rid of all my problems but I want to make sure that I solve this so as not to create more possible issues. Any more input??

thanks

RotaryResurrection

iTrader: (8)

I'll have a quick go at it. FIrst off, this wiring harness discrepancy is no issue...I've done it before, and it will not cause running problems if done correctly. TO bypass the injector resistor pack (which btw should NOT be used in conjunction with the high impedance injectors you have in the car) you simply connect all 5 wires on that plug...the center is 12vdc+ supply, and the 4 surrounding wires are leads to each injector....you're completing the circuit between the center supply wire and the outer wires. FOr this, you can cut the oval plug off, and solder all 5 wires together in a bundle, or you can use small jumper wires inserted into the plug end. OR, the neatest method, you could purchase a used injector resistor pack, pictured above, and cut off the resistor pack, keeping just the other end of the plug, and wires...and then do teh soldering on that end (to prevent messing up a perfect new engine harness).


Second, the new primaries should have no effect whatsoever on fuel pressure, or the secondaries. THe fuel pump and FPR determine pressure...you could have 10 injectors hooked up and never INCREASE fuel pressure. I'm wondering if you didn't get something other than 550 injectors. Perhaps flow test them just to be sure? The procedure is easy to do yourself, or get them done by someone else. Sounds like you might have gotten ahold of something like a 680 or 720.

When you say that your AF gauge is in the red at idle, red means LEAN, green means RICH, yellow means normal/stoich. Perhaps you typed the wrong thing, or perhaps you're looking at this backwards.

Worst case scenario, if you continue to have too much fuel to deal with, get an afc and turn it down. Having too much fuel in an rx-7 is a better problem than not enough, which is what most of us have.

Another option for you here is to buy 4 LOW impedance 550's and put them in, along with the stock resistor pack. That way, not only are you sure your resistance issue is solved, but you're also sure you have the right size injectors. Get a set from someone who can tell you their history, i.e. "they ran fine in my car".

phinsn98

iTrader: (2)

You gave me an interesting idea in the fact that ONE of the injectors is not a 550 cc high inpedence injector. The one injector that locked up initially we found one that was color coded the same but the key was not correct for the year. We just shaved the key off and went from there. I'd be shocked if that's the case but hey I'll look into anything. What type of wheels do you have on your vert Kevin? I just picked up a 90 vert...your's looks sweet.

RotaryResurrection

iTrader: (8)

Just because part numbers are the same, doesnt mean injectors are. Mazda gave the 87 LI injectors the same part number as the 88 HI ones. For what reason, I do not know. They did it for the NA's, too.

The vert rims are 18" konig imagines in opal. Here are some closeups.

https://www.rx7club.com/showthread.php?t=330908