kenneth_ugalde

I have an N/A '86 with a fresh rebuilt engine. New Rotor Housings (S5), new side plates (S4), new rotor kit (all that touches the rotors), all new gaskets, new water pump, new OMP with billet alum. adapter for 2 cycle oil, Mazdatrix Oil Thermo Pellet, oil pressure sender, water temp sender, Oil meter condenser, ultrasonic cleaning of the injectors, new Trailing Coil with igniters, new MSD plug wires, New rad, new 185 Black Magic X-treme FAL e-fan with SPAL fan Controler, K&N cone air filter with CNC machined MAF adapter by Bonez, Racing Beat headers, Bonez High Flow Cat, new O2 Sensor, EGR delete plate, all new water hoses, Oil cooler hoses.
I also have added a ground wire to the vaccum sensor under the hood, (it is a well known mod for '86) and replaced the ground cable going from the UIM to the firewall, with 10 Ga. wire.

One of my problems is that when decelerating, the engine runs smooth until it reaches 1500 RPM. From there to idle, it runs rough and the engine sound is different, until it reaches idle speed.
The idle is smooth and solid. It starts well and on the first try, cold or hot. It climbs to 2500 or so like it should when hot and settles to idle after a few secs, and stays at 1500 or so when cold, until warm.

I am not sure if all the vaccum hoses (which I don't wan't to delete) are in the right place. I have a FSM but the graphic in it is not very good.

I also replaced the ring terminal for the injector ground under the UIM wanting to fix the 3800 RPM hesitation, but after I did that, not only did the decel and hesitation problem was not fixed, but now the car has random episodes of what feels like fuel cut at high RPM, and the engine sputters and wants to die for a few secs after that.

I need help regarding these issues and I appologize for the loooong thread, but I'm just giving all the information that I think is important, not wanting to do a mod list.

Thanks.

walken

iTrader: (6)

test your tps

MMoore4545

iTrader: (7)

yep TPS is the culprit, just because your check light isn't on doesn't mean the TPS is 100%

kenneth_ugalde

I checked the TPS as stated in the FSM, and set it with the tool Mazda sells for that purpose. Also, I might be wrong but I think '86's don't have a check engine light. I know mine doesn't.

It has to be something else.

kenneth_ugalde

I can't believe no one has another sugestion on what this might be.

There's lots of knowlegeable people here that might have gone through this before.

Help !!!

kenneth_ugalde

Bumpty-bump

Brodie121

iTrader: (8)

no there's a check engine light, up in the idiot light cluster

misterstyx69

iTrader: (142)

have you checked the thermowax on the throttle body to make sure that it is not clogged up?

djchiptoothsfc

iTrader: (2)

Ive had my car overheat to the point that it looked like a fog machine, motor blew, oil leaked and my check engine light still didnt pop up. Its probably a stupid Emissions solenoid somewhere.

calpatriot

There is a valve which is supposed to inject extra air from the air pump into the intake tract during decelleration. If it is not working right, or is not hooked up, it might be the culprit.

A quick check can be made by rigging up a 12v LED to the 'green lamp' pin (bottom center) on the test connector. Once you are warmed up, it should show on (green--if u use a green LED) at idle; green during acceleration; flashing on and off during steady cruise; and OFF during deceleration.

If it is not going to OFF during deceleration, the mixture is too rich (green is rich, off is lean), and is probably due to the air valve system not working. Could be the valve, tubing, wiring, air pump, or air pump belt.

No, your 86 has no check engine lamp. you can make one pretty easily; wire two 12v LEDs to the circuits going out to the test connector, one for the 5s lamp, and one for the 1s. Mount them whereever you like. They should come on for 3 sec after start, and then go out. Any flashing is a trouble code, and the equivalent of a check engine light.