Lean issue when secondaries "kick on"
02-01-11, 05:06 PM
#101
Doesn't the stock fp cuircut run lower voltage for cruising/idle for fuel economy and then (supposedly) give full voltage under load ?
Is that feature the reason my figures are low (thus meaning it would need to be eliminated). Or is corrosion/ bad solder joints/crimps the culprit? (allowing me to keep the "dual voltage" feature, assuming the faulty wires/connections arr replaced)
Is that feature the reason my figures are low (thus meaning it would need to be eliminated). Or is corrosion/ bad solder joints/crimps the culprit? (allowing me to keep the "dual voltage" feature, assuming the faulty wires/connections arr replaced)
02-01-11, 05:08 PM
#102
the added resistance usually comes from the relays which have buildup on them from years of use. those figures aren't super low but 7volts? no, that's not normal even for the 2 step during cruising. unless you really need the FPR solenoid and 2 step relay system for emissions it is more reliable to bypass them both and adjust the maps for a more accurate constant tune. i'm sure even with the Rtek that it could be tuned to still pass emissions regardless of eliminating the 2 step system.
Last edited by RotaryEvolution; 02-01-11 at 05:10 PM.
02-01-11, 05:27 PM
#103
No emissions here, I just want to retain some shred of fuel economy since this is my daily. But I guess I'll have to adjust the maps to do that, because reliability if priority 1 and if that can't be had w/ the stock relays they've got to go.
02-01-11, 05:32 PM
#104
Might want to bypass the Fuel Pump Relay and Resistor as the relay when working effectively should increase voltage to the fuel pump when going full throttle. The relay has a six wire plug which is to be disconnected and you will find two Blue/Green wires and three Blue/Red wires. Jumper one of the Blue/Green to one of the Blue/Red and this will bypass the Resistor relay and see what happens.
02-03-11, 12:22 PM
#105
I can see how that would be annoying to deal with at a tuning sessions, its infuriating just trying to drive around on the street, lol.
Good point on the 4th gear pulls, but it was easier to slowly build boost and make observations in 4th, I never did any WOT pulls in 4th.
So After lots of reading/research I decided to follow the re-wire wrieup on 1300cc.com . The reason being, despite the rtek being able to adjust fuel/timing, it is still based on the stock map which takes into account the variable voltage feature in the stock pump wiring. Additionally, I am still running the stock turbo which has been taken to its limits by unmodded fuel systems bandaid tuning solutions. Therefore the decrease in fuel economy wouldn't have been offset by any appreciable gain in performance or reliability (I have only been able to fine 1 case of either the resistor or relay failing).
Instead of trying to mount the resistor behind the tail light where it would be close to wires, I put it in the location of the power antenna motor (which I removed a while ago) the mounting holes even lined up
Overview of everything connected for testing...
Final locations for all components...
Close up of Relay/connector area. I had a few extra protective boots from when I relocated my battery, figured I could put one to good use. I de-pinned the stock fuel pump connector to run larger ground/power wires. I should upgrade the wires on the pump side too, the ground would be easy, but I haven't figured out how to get that little gel cap off the (+) wire where it enters the tank. Stock wires should be fine for an FD pump....
Good point on the 4th gear pulls, but it was easier to slowly build boost and make observations in 4th, I never did any WOT pulls in 4th.
So After lots of reading/research I decided to follow the re-wire wrieup on 1300cc.com . The reason being, despite the rtek being able to adjust fuel/timing, it is still based on the stock map which takes into account the variable voltage feature in the stock pump wiring. Additionally, I am still running the stock turbo which has been taken to its limits by unmodded fuel systems bandaid tuning solutions. Therefore the decrease in fuel economy wouldn't have been offset by any appreciable gain in performance or reliability (I have only been able to fine 1 case of either the resistor or relay failing).
Instead of trying to mount the resistor behind the tail light where it would be close to wires, I put it in the location of the power antenna motor (which I removed a while ago) the mounting holes even lined up
Overview of everything connected for testing...
Final locations for all components...
Close up of Relay/connector area. I had a few extra protective boots from when I relocated my battery, figured I could put one to good use. I de-pinned the stock fuel pump connector to run larger ground/power wires. I should upgrade the wires on the pump side too, the ground would be easy, but I haven't figured out how to get that little gel cap off the (+) wire where it enters the tank. Stock wires should be fine for an FD pump....
02-03-11, 02:33 PM
#106
Good job man! Hope that fixes it!
So, If your pump voltage is low, it might have the pressure at Idle, but most likely dropping off when you increase rpms and when the secondaries come online causing it to go lean. Now you have cranked the rtek to 550/550 with a 550/720 Inj. combo (essentially +30% more fuel) and you can actually boost it. Makes sense to me that this is your issue and your lean, not rich...
Edit, and when the pressure regulator begins to raise the pressure you get less flow and with 8v to the pump = not enough for a FI rotary engine.
So, If your pump voltage is low, it might have the pressure at Idle, but most likely dropping off when you increase rpms and when the secondaries come online causing it to go lean. Now you have cranked the rtek to 550/550 with a 550/720 Inj. combo (essentially +30% more fuel) and you can actually boost it. Makes sense to me that this is your issue and your lean, not rich...
Edit, and when the pressure regulator begins to raise the pressure you get less flow and with 8v to the pump = not enough for a FI rotary engine.
02-03-11, 03:47 PM
#107
Indeed!
10.2v idle/cruise
10.5 cruise - 13.5 wot
Its raining so I didn't stay in it, but I went wot just long enough to see 13.5v. It started to bog (much smoother than the previous "stutter") due to the 550/550 setting when then secondaries came on. I'm switching the rtek back to 550/720 and all should be good....
10.2v idle/cruise
10.5 cruise - 13.5 wot
Its raining so I didn't stay in it, but I went wot just long enough to see 13.5v. It started to bog (much smoother than the previous "stutter") due to the 550/550 setting when then secondaries came on. I'm switching the rtek back to 550/720 and all should be good....
02-03-11, 05:30 PM
#109
I had this same issue, what kind of secondaries do you have? If was actually boost related, i had the wrong injector seals and boost would push the injector into the rail out of it's seat and the boost would spray the fuel out from around the port in the intake manifold where the injectors went in.
My injectors are PTE.
Edit: NVM just now read your most recent post
My injectors are PTE.
Edit: NVM just now read your most recent post
02-03-11, 05:35 PM
#110
Rotary Freak
Somewhat related............it's a shame some people run a seperate wire from the engine bay to power the fuel pump.....when there is already a very good source of batt voltage there in the rear window/heater relay. Has batt voltage 24/7 and is a large ga wire colored white.
That relay is shown in one of your fist picture posted above. Seems the elec plug is off it though for some reason. I use that white wire to power my trailer lights instead of the stk tail light wiring.
That relay is shown in one of your fist picture posted above. Seems the elec plug is off it though for some reason. I use that white wire to power my trailer lights instead of the stk tail light wiring.
02-03-11, 06:43 PM
#111
Somewhat related............it's a shame some people run a seperate wire from the engine bay to power the fuel pump.....when there is already a very good source of batt voltage there in the rear window/heater relay. Has batt voltage 24/7 and is a large ga wire colored white.
That relay is shown in one of your fist picture posted above. Seems the elec plug is off it though for some reason. I use that white wire to power my trailer lights instead of the stk tail light wiring.
That relay is shown in one of your fist picture posted above. Seems the elec plug is off it though for some reason. I use that white wire to power my trailer lights instead of the stk tail light wiring.
Oh, THAT'S what that thing is for? lol I will keep that connector in mind for future modifications however. The plug was off because I used its original location for the new fuel pump ground, wanted to make it as short as possible and there was already a threaded hole 5" to the left....kinda worked perfectly.
Whats really a shame is that speaker wire you have to run to connect those two wires from the original plug location for the resistor! Snaking that thing through the old ABS grommet, under the cardboard panels by the rocker panels, and along the support beam for the storage bins, is what caused this project to go on into the night.
02-03-11, 10:10 PM
#112
Recycle, get a turbo!
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I'm really glad you figured it out. I just read the whole post, I am having the same problem with my s5 turbo rebuild with the sudden loss of all power when I open up the throttle. This thread was very helpful.
02-04-11, 12:33 PM
#113
I changed the settings back to 550/720 and voltage to the pump is good. Its still down on power when the secondaries come on, but its running rich now instead of lean. I suspect this is due to the combination of fd fuel pump, increased voltage from rewire and the 30psi fuel pressure @ idle. But that can be tuned. I'll trim 5% after the secondaries come on and see where that gets me......time to get that wideband installed.
Yeah, I almost feel like it should be archived as we've been through just about every possible hesitation/leaning theory and test.
04-12-11, 05:09 PM
#118
That helped, but in my case it didn't completely solve the problem.
I have switched the secondary ins at the ecu and spun the cas to verify that both secondary injectors do click when given the signal. However the car still falls on its face when the secondaries are supposed to come on (in boost or above 3300rpm). At this point I'm out of ideas, I'll pull the uim ...AGAIN and see if maybe one (or both) of the secondaries has a compromised connection but other than that I have no idea
I have switched the secondary ins at the ecu and spun the cas to verify that both secondary injectors do click when given the signal. However the car still falls on its face when the secondaries are supposed to come on (in boost or above 3300rpm). At this point I'm out of ideas, I'll pull the uim ...AGAIN and see if maybe one (or both) of the secondaries has a compromised connection but other than that I have no idea
04-12-11, 09:37 PM
#119
The secondary injector staging issue with the S5 n/a which Karack was referring to is described here:
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/power-drop-noticeable-hesitation-issue-high-6300-rpm-802779/#29
You may want to try bypassing the wiring harness by running a wire from the injector to the ECU, as described in post #29.
The earlier posts discuss a couple of changes that resulted in improvements, but did not eliminate the problem entirely:
-- clean / service / flow-test the fuel injectors
-- try known good turbo injectors
-- change fuel pump to increase fuel pressure
-- bypass the fuel pump relay, resulting in fuel pump voltage increasing from 6.7 to 10.6 volts.
Sound familiar.....?
https://www.rx7club.com/2nd-generation-specific-1986-1992-17/power-drop-noticeable-hesitation-issue-high-6300-rpm-802779/#29
You may want to try bypassing the wiring harness by running a wire from the injector to the ECU, as described in post #29.
The earlier posts discuss a couple of changes that resulted in improvements, but did not eliminate the problem entirely:
-- clean / service / flow-test the fuel injectors
-- try known good turbo injectors
-- change fuel pump to increase fuel pressure
-- bypass the fuel pump relay, resulting in fuel pump voltage increasing from 6.7 to 10.6 volts.
Sound familiar.....?
06-16-11, 01:41 PM
#120
Just so this thread is conclusive for anyone who may find it useful in the future...
The lean issue was not completely eliminated by the fuel pump rewire. In fact over the next few weeks it continued to get worse, to the point where any boost over 3500 rpm would shot the afr into the 20's. I tried every solution mentioned I'm this thread and even tried to "out tune" the lean condition by adding 10% fuel @ 0psi and an additional 1% for every psi after that. Nothing worked.
I putted around town for a couple months since I had no new ideas, but finally got fed up, and decided to retest everything. The only test I didn't do the first time was test the spray paten on the injectors (since I heard them click when tested, the spray pattern was confirmed when I had them cleaned, and I was by myself, and only have 2 hands.)
I talked to a friend of mine who actually had an injector fail open. He stated that he could gear it spraying even in the car. So I pressurized the fuel rail and hit each of the secondaries w/ a 12 lead (and ground). To my surprise they sounded like small rocket engines!
Once everything was reassembled I went for a test drive, afr was down to 10 by 4 psi and dropped to 9.2 quickly thereafter. Time for a retune!
Looking back it seems most likely that the break in period for my clutch (2months) is what caused my initial problem. The secondaries went too long w/o use and became at least partially clogged/stuck. My first round of tests and fuel pump rewire must have helped unclog one injector making it seem like the problem was solved, however another long period of none use must have allowed that injector to become clogged/stuck again, leading to the "boost wall". Since under normal operation, the injectors are only open for miliseconds, it must not have been enough to unstick them, but forcing them open for 3-4 seconds at a time @ 40 psi seems to have done the trick.
Moral of the story: a redline a day is for more than just carbon deposits, drive your car like its meant to be driven....it will thank you.
The lean issue was not completely eliminated by the fuel pump rewire. In fact over the next few weeks it continued to get worse, to the point where any boost over 3500 rpm would shot the afr into the 20's. I tried every solution mentioned I'm this thread and even tried to "out tune" the lean condition by adding 10% fuel @ 0psi and an additional 1% for every psi after that. Nothing worked.
I putted around town for a couple months since I had no new ideas, but finally got fed up, and decided to retest everything. The only test I didn't do the first time was test the spray paten on the injectors (since I heard them click when tested, the spray pattern was confirmed when I had them cleaned, and I was by myself, and only have 2 hands.)
I talked to a friend of mine who actually had an injector fail open. He stated that he could gear it spraying even in the car. So I pressurized the fuel rail and hit each of the secondaries w/ a 12 lead (and ground). To my surprise they sounded like small rocket engines!
Once everything was reassembled I went for a test drive, afr was down to 10 by 4 psi and dropped to 9.2 quickly thereafter. Time for a retune!
Looking back it seems most likely that the break in period for my clutch (2months) is what caused my initial problem. The secondaries went too long w/o use and became at least partially clogged/stuck. My first round of tests and fuel pump rewire must have helped unclog one injector making it seem like the problem was solved, however another long period of none use must have allowed that injector to become clogged/stuck again, leading to the "boost wall". Since under normal operation, the injectors are only open for miliseconds, it must not have been enough to unstick them, but forcing them open for 3-4 seconds at a time @ 40 psi seems to have done the trick.
Moral of the story: a redline a day is for more than just carbon deposits, drive your car like its meant to be driven....it will thank you.
07-24-11, 09:41 PM
#121
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I'm going to send mine to be cleaned again. I have been having the same issue for a month now, and I just came across your post. So far I replaced the fuel rail, pump, afm, reset the rtek 2.1, and coils. This problem started occurring after driving the car with no boost for about 3 or 4 weeks trying to save gas.... At the 1st start of the day the car can boost, can boost until its fully warm then it always hits that wall sadly... Thanks to this post I believe I that this is the issue and I can finally move on!!!
01-17-12, 10:15 PM
#122
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I know this is an old post. Been searching for days. I read through the whole thing, but I'm not sure it's what my problem is.
1988 T2
Here are my symptoms:
1. Car will not go into boost at all. As soon as it sees boost (no matter what RPM), it hesitates, jerks, bogs, sputters, hits a wall and goes nowhere real fast.
2. Cannot press down on the throttle more than 1/4-1/3 of the way without it bogging, hesitating, jerking, etc. (so once again, no boosting)
3. If I slowly ease on the throttle (1/4-1/3 down, only staying in vacuum), I can get past 4000rpms
4. Car randomly dies at idle. Also when coming to stop light and depressing the clutch, rpms drop quickly and car dies. If I pull up to a stop light and gradually let the rpms drop (by downshifting, blipping throttle), it will idle at 750-800 fine, but sometimes it will dies after 10 seconds of idling fine as well.
5. If parked and I mash on the pedal, it hesitates, jerks, bogs, etc. and rpms do not rise. If I press the pedal a little bit (in vacuum), it will rev all the way.
Car has been sitting for a very long time by previous owner. He started it once every week or so and ran it, but hasn't driven it in years.
So far I have done the pressure sensor ground, new spark plugs, fuel pump, fuel filter, catalytic converter. Changing spark plug wires in a couple days.
Anyone have any ideas? Please help!
1988 T2
Here are my symptoms:
1. Car will not go into boost at all. As soon as it sees boost (no matter what RPM), it hesitates, jerks, bogs, sputters, hits a wall and goes nowhere real fast.
2. Cannot press down on the throttle more than 1/4-1/3 of the way without it bogging, hesitating, jerking, etc. (so once again, no boosting)
3. If I slowly ease on the throttle (1/4-1/3 down, only staying in vacuum), I can get past 4000rpms
4. Car randomly dies at idle. Also when coming to stop light and depressing the clutch, rpms drop quickly and car dies. If I pull up to a stop light and gradually let the rpms drop (by downshifting, blipping throttle), it will idle at 750-800 fine, but sometimes it will dies after 10 seconds of idling fine as well.
5. If parked and I mash on the pedal, it hesitates, jerks, bogs, etc. and rpms do not rise. If I press the pedal a little bit (in vacuum), it will rev all the way.
Car has been sitting for a very long time by previous owner. He started it once every week or so and ran it, but hasn't driven it in years.
So far I have done the pressure sensor ground, new spark plugs, fuel pump, fuel filter, catalytic converter. Changing spark plug wires in a couple days.
Anyone have any ideas? Please help!
01-17-12, 10:44 PM
#123
What did you do to the Boost Sensor? Change it or check it according to spec. Spec would be 2.3 to 2.7 volts at the Brown/Red wire w/key to on and the vacuum hose removed and capped. Is the TPS within spec, which would be 1 volt w/key to on at the Green/White wire from the TPS.