1986 N/A wont rev past 4,000RPM
#151
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There have been several threads with cars that would not rev over 4000rpm. It turns out a LOT of them had no power to one of the secondary injectors plugs. Power can be checked by getting a meter out and backprobing the two secondary wires at the ECU with key ON. Should read batt voltage. No batt voltage on one of them means you've a open circuit to or from that injector.
I've got my multi-meter, my stethoscope, and hopefully an extra set of hands.. I'd love to get the injectors fireing, the TPS adjusted, and perhaps start on replaceing my cat. (BTW, ~$320 from NAPA for a two cat w/ return air to replace the factory three cat. Mazda wanted ~$2800).
If all goes well, next week I'll have a daily driver...almost 7 months to the day I baught it.
#152
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Please tell me if my logic is BS.
Back probed the all 4 injector lines @ the ECU. ~12vdc on each one. From the diag I looked at, the grounded side of the injectors passes through the resistors and then to the main relay, not the ECU. Technically I could still have a break between the injector and the ECU, or between the injectors and the main relay.
I'm going to have to pull the injector connectors and retest. I should have ~12vdc on the line from the ECU & I should have the resister value between the injector and the main relay.
Or better yet.... from the ECU, unplug the cannon connector for the injectors and check for resistance to ground. infinity or 0 = bad.
Back probed the all 4 injector lines @ the ECU. ~12vdc on each one. From the diag I looked at, the grounded side of the injectors passes through the resistors and then to the main relay, not the ECU. Technically I could still have a break between the injector and the ECU, or between the injectors and the main relay.
I'm going to have to pull the injector connectors and retest. I should have ~12vdc on the line from the ECU & I should have the resister value between the injector and the main relay.
Or better yet.... from the ECU, unplug the cannon connector for the injectors and check for resistance to ground. infinity or 0 = bad.
#153
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resistance results - ~.64 ohms across each injector form the ecu cannon connector (disconnected from the ecu) to ground.
I'll have to test with the engine running to verify if the injectors are cycling. Time for an extra pair of hands (or feet as the case may be. )
I'll have to test with the engine running to verify if the injectors are cycling. Time for an extra pair of hands (or feet as the case may be. )
#154
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Voltage results while running. ~12vdc on primaries, 0vdc on 2ndaires while at idle. I'll need an extra body to bring the idle up while I watch the DMM.
Side note, I think I still have too much backpresure from the cat. At idle the aux ports are actuating.
Side note, I think I still have too much backpresure from the cat. At idle the aux ports are actuating.
#155
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Todays Update - I've been adding 3 holes to my cat every day. Each time my engine starting and response has improved. Today I was able to acheave 40 mph.. Mind you, under load I can not hit 4k rpm, but I'm close. I'm running at about 3k rpm when I hit 40 in 3rd, yesterday I could not get over 35, and 3rd gear was right out of the question.
I've also noticed my aux ports are no longer actuating at idle.
It looks like a cloged cat is a major part of my issues. As soon as I get a new set of Cat's from NAPA I'll get it replaced. Untill then, I'll just keep on drilling a few holes until I get enough air flow to get the RPM's up, or until it stops making a differance.
I've also noticed my aux ports are no longer actuating at idle.
It looks like a cloged cat is a major part of my issues. As soon as I get a new set of Cat's from NAPA I'll get it replaced. Untill then, I'll just keep on drilling a few holes until I get enough air flow to get the RPM's up, or until it stops making a differance.
#157
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I contemplated the idea. I'd like to stay friends w/ the neighbours. And the lift I'm going to use when I replace the cats is a 45 min drive away. I don't think I could stand the drive w/o cats. It's starting to get a bit loud already w/ 12 holes.
#159
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I don't have a fuel pressure gauge, but I know my top rail is getting fuel (had a torn o-ring on an injector) I suspect I could "rent" a guage from advanced or AZ. Cleaning the "sock" is in my to-do list, already replaced the main filter.
I haven't seen any codes yet (check engine lite has not come on). But worth checking again. Will the ECU kick out codes w/o the check engine lite illuminating?
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I don't have a fuel pressure gauge, but I know my top rail is getting fuel (had a torn o-ring on an injector) I suspect I could "rent" a guage from advanced or AZ. Cleaning the "sock" is in my to-do list, already replaced the main filter.
I haven't seen any codes yet (check engine lite has not come on). But worth checking again. Will the ECU kick out codes w/o the check engine lite illuminating?
If you pull off a connector to a secondary injector, you should be able to see 12v between one of the two pins in the connector and ground. The injector works when the ECU pulls the other pin to ground. If the 12v is not there, the injector will never come on; likely an open in the wiring harness.
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#163
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I'm about ready to pull my UIM and LIM off and replace the injectors and see what other disasters I can find.
Mark all of the vacuum lines as you pull them off, so you do not get them mixed up when you reassemble.
If you are going to go through this amount of work, recommend you send out the injectors for professional cleaning and testing.
Have a new gasket ready for the UIM LIM junction (mazdatrix calls it the center gasket...)
I used Permatex #2 on both sides of the gasket, just to make sure there were no leaks...
I found multiple points of deterioration in the wiring, and the plastic shells of the injector connectors were crumbling in my hands... new injector connectors are available for $10 each; I did all 4.
Plan on having to cut off the two coolant hoses (3/8"). New molded ones are available from Mazdatrix, or you can just use 3/8" hose. Have some 5/16 fuel injection hose ready to replace those going to and from the fuel rails, they may not come off intact either.
But, before you do all this, check to make sure there is 12v on one pin of each secondary fuel injector connector... without power, none of this will help...
#164
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Wow, go on vacation and now I have a bunch of work to catch up on. Thanks guys for the sugestions. I will follow through as quickly as possible.
Just a note. As I reduce back presure from the cat, the responsiveness and max rpm have improved. I managed to get over 4k RPM last nite in 3rd, and it's running cooler. I'm going to check the fuel sock when I replace the carpet in the back, and order the replacement cats when I can get some time on a lift.
BTW, anyone have any expereance w/ the CAT's from Eastern Catalytic - (pn: 40137)
Just a note. As I reduce back presure from the cat, the responsiveness and max rpm have improved. I managed to get over 4k RPM last nite in 3rd, and it's running cooler. I'm going to check the fuel sock when I replace the carpet in the back, and order the replacement cats when I can get some time on a lift.
BTW, anyone have any expereance w/ the CAT's from Eastern Catalytic - (pn: 40137)
#165
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I went with the CATCO #4689. A little more ( $160+shipping) then the Eastern Catalytic, but a better waranty. While I need to go through basic system adjustments to get the idel back under control, I would have to say my injectors are fine. I can run the RPM's well over 4k under load. Even managed 55 MPH in third gear for the first time since last fall.
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Go to the two secondary injector connectors and pull 'em off. Key to ON. See if one wire in each connector has batt voltage or not. Should. Sounds like one of the two is off the injector.
Or driver the car using little pedal until you reach 5000rpm. Should. Then stomp the pedal at 5000 and see what happens. IF the engine starts acting crummy with light throttle and reaching appox 3500-3800 rpm.........then suspect the boost sensor is not seeing vacuum from the engine.
And or go to the ECU small plug and make sure each of the four light green wires have batt voltage with the key to ON. Check at the plug, not the jack on the ECU. If you get batt voltage at each light green wire on the small ECU plug, the wiring is intact for each of the injectors.
Then go to pin 2B and make sure it has 3.5-4.5vdc with the key to ON, engine off. 2B is the middle ECU plug and the counting is from looking into the wire side of the plug in a up/down fashion. 2B would then be on the lower row......far right. Brown/red wire.
Go to the two secondary injector connectors and pull 'em off. Key to ON. See if one wire in each connector has batt voltage or not. Should. Sounds like one of the two is off the injector.
Or driver the car using little pedal until you reach 5000rpm. Should. Then stomp the pedal at 5000 and see what happens. IF the engine starts acting crummy with light throttle and reaching appox 3500-3800 rpm.........then suspect the boost sensor is not seeing vacuum from the engine.
And or go to the ECU small plug and make sure each of the four light green wires have batt voltage with the key to ON. Check at the plug, not the jack on the ECU. If you get batt voltage at each light green wire on the small ECU plug, the wiring is intact for each of the injectors.
Then go to pin 2B and make sure it has 3.5-4.5vdc with the key to ON, engine off. 2B is the middle ECU plug and the counting is from looking into the wire side of the plug in a up/down fashion. 2B would then be on the lower row......far right. Brown/red wire.
#168
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1986 s4 na. I can get passed the threshold with light throttle but when you hit the gas hard it hits the wall. Could a had apex seal cause high Rev performance problems? just yesterday i noticed when i do get passed 4k and hit 7k and shift there is quite a bit of blue smoke
#169
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You have 4 wires at the pressure sensor. Black/White reads 12 volts w/key to on. Brown/White reads 5 volts w/key to on. You already know the Brown/Red wire reads 3.5 to 4 volts w/key to on. The 4th wire is the ground wire and thus should read close to 0 volts w/key to on (on an 86 NA the ground wire is Brown with a stripe). Remeasure each of these wires and post the results.
#170
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You have 4 wires at the pressure sensor. Black/White reads 12 volts w/key to on. Brown/White reads 5 volts w/key to on. You already know the Brown/Red wire reads 3.5 to 4 volts w/key to on. The 4th wire is the ground wire and thus should read close to 0 volts w/key to on (on an 86 NA the ground wire is Brown with a stripe). Remeasure each of these wires and post the results.
#171
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The readings are supposed to be taken w/the sensor plugged in because the Brown/Red wire is an output wire and if unplugged then you're not able to get a reading from the sensor, plus if there were an internal problem to the sensor or connector then it would not show up w/the tests taken w/the sensor unplugged.
#172
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Wont rev past 3k mpms
I have a 86 w a tii swap and I just got car back front the builder and drove it 50 miles home and belt started to become lose the closer I got to my home I' parked it when I got back and when I woke up in more morning it was completely dead tried jumping it and it started as soo as I took the jumpers off the terminals she shut right off I changed ecu alt and battery new and now she wont pass 3krms
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Captain Hook
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