After months of messing with it and searching possibly every thread/forum/piece of info I could find on the issue I'm having, I've finally decided to post for help from my fellow mazda protege community.
Here's the issue...
Once the car warms up, it hesitates and stumbles at specific RPMs. Similar to a missfire or hitting a governor.
Here's the background to the problem...
I decided to change over to the 1.8 coil conversion and long reach plugs. (Eng is the stock 2.0 fs-de) the car ran fine before I changed everything out...valve cover from 626, coils, wires, plugs...then after the conversion it ran like total crap, stumbling all over the place, not driveable at all. Being the packs were off a junkyard car, I ordered brand new ones. Replaced them, problem got better, but still bad. Changed out the wires with another new set, no change, put in normal spec plugs, seemed to make it less erratic, but now the car stumbles at 2800-3000 rpm pretty much on the dot. Decided that many people do the 1.8 conversion, so it must be another issue. Only other part touched at the time was the swap of valve covers, so I thought that the cam angle sensor might have goofed out of no where...changed that, same issue, no change. Started changing checking sensors. Here's the list:
MAF - checked with meter/cleaned/swapped with new one
Cam Sensor - checked with meter/changed with new one
Crank sensor - checked with meter/measured clearance from teeth on pully. New one on the way, haven't changed part yet.
EGR - cleaned, checked with meter, have another one, haven't changed yet.
Coil packs - changed twice once used then new ones.
Wires 1.8 - changed with new twice first set Bocsh second set Duralast.
Plugs - new long reach spec, then new stock NGK copper .044 gap.
Intake - scanned for leaks, it's aluminum Injen cold air, so no cracks in it or connectors.
ECU - reset multiple times.
Fuel pump - new filter housing/screen
TPS - checked with meter
Basically I have ran a multimeter through the whole car and every sensor I could think of using specs from the FSM. Nothing checks bad. I've replaced a bunch of sensors, still no change. In frustration I decided to put back my old 2.0 packs and Nology wires. The problem calmed down a bit, and the car is better, but now it stumbles at around 1800 rpm and 3000 rpm range. When pressing the throttle it hesitates up slowly (about 5-7% peddle) stumbles a bit on those two rpm ranges, then revs hard after 3100 rpm as if I pushed the gas harder, not out of control fast, but normal quick vs the laggy feeling from idle to 3k. The old 2.0 packs and wires make it less harsh than the 1.8 setup where it felt like I hit a tree at 3000 rpm. This happens in all gears and the faster I punch it, the worse it does it. If I ease the gas, it's not as crazy.
Another bit of info...there are no CEL codes either.
I'm about tired of throwing parts at this thing and want to pull the motor out and smash it with a truck, so any help will be much appreciated, I'm stumped.
Here's the issue...
Once the car warms up, it hesitates and stumbles at specific RPMs. Similar to a missfire or hitting a governor.
Here's the background to the problem...
I decided to change over to the 1.8 coil conversion and long reach plugs. (Eng is the stock 2.0 fs-de) the car ran fine before I changed everything out...valve cover from 626, coils, wires, plugs...then after the conversion it ran like total crap, stumbling all over the place, not driveable at all. Being the packs were off a junkyard car, I ordered brand new ones. Replaced them, problem got better, but still bad. Changed out the wires with another new set, no change, put in normal spec plugs, seemed to make it less erratic, but now the car stumbles at 2800-3000 rpm pretty much on the dot. Decided that many people do the 1.8 conversion, so it must be another issue. Only other part touched at the time was the swap of valve covers, so I thought that the cam angle sensor might have goofed out of no where...changed that, same issue, no change. Started changing checking sensors. Here's the list:
MAF - checked with meter/cleaned/swapped with new one
Cam Sensor - checked with meter/changed with new one
Crank sensor - checked with meter/measured clearance from teeth on pully. New one on the way, haven't changed part yet.
EGR - cleaned, checked with meter, have another one, haven't changed yet.
Coil packs - changed twice once used then new ones.
Wires 1.8 - changed with new twice first set Bocsh second set Duralast.
Plugs - new long reach spec, then new stock NGK copper .044 gap.
Intake - scanned for leaks, it's aluminum Injen cold air, so no cracks in it or connectors.
ECU - reset multiple times.
Fuel pump - new filter housing/screen
TPS - checked with meter
Basically I have ran a multimeter through the whole car and every sensor I could think of using specs from the FSM. Nothing checks bad. I've replaced a bunch of sensors, still no change. In frustration I decided to put back my old 2.0 packs and Nology wires. The problem calmed down a bit, and the car is better, but now it stumbles at around 1800 rpm and 3000 rpm range. When pressing the throttle it hesitates up slowly (about 5-7% peddle) stumbles a bit on those two rpm ranges, then revs hard after 3100 rpm as if I pushed the gas harder, not out of control fast, but normal quick vs the laggy feeling from idle to 3k. The old 2.0 packs and wires make it less harsh than the 1.8 setup where it felt like I hit a tree at 3000 rpm. This happens in all gears and the faster I punch it, the worse it does it. If I ease the gas, it's not as crazy.
Another bit of info...there are no CEL codes either.
I'm about tired of throwing parts at this thing and want to pull the motor out and smash it with a truck, so any help will be much appreciated, I'm stumped.