Too rich to start? N/A to T2 swap w/ Walbro
04-25-18, 11:32 AM
#1
mattfromthepier
Thread Starter
Too rich to start? N/A to T2 swap w/ Walbro
The car is an '88 gtu with a 87' T2 swap, rtek 1.8, 4x750cc RC injectors, walbro 255lph fuel pump, 4x bur9eqp NGK plugs, and safc2 hooked up to the pressure sensor instead of throttle position. The car ran so well for years it was miraculous until recently, when I installed a msd 6aL onto the leading coil and it sputtered around the 3k rpm range. This is when the multi spark discharge should kick in so i looked into it, concluded it was faulty, and rewired the leading coil to its factory arrangement. I started the car and it fired right up and ran smooth for my neighborhood warm up cruise, when I got to the nearest highway i gave it a bit of throttle to build some boost and it sputtered and shut right off and wouldn't start again so I towed it home with the trusty toyota corolla. I noticed when i got it home that my fuel pressure gauge was reading zero PSI so i checked voltage at the pump and there was none.
SO... I wired a 4 pin relay and fancy toggle switch below the dash and have the fuel pump (255lph Walbro) connected directly to the battery from the relay/switch and there is battery voltage at the pump, but the car hasn't started since. So is it possible I am dumping a ton of fuel, too much for the start map on the factory t2 ecu? I ran the battery out and after letting it charge a while (jumpered with the trusty corolla), it was fully juiced and perhaps the starter spun fast enough to skip the start map causing it to fire up but run terribly, is this scenario possible? At this point i should have messed with the safc2 to see if it could help improve idle/ low rmp but it ran so boggy i wanted to scream and cry so instead I let it sputter out. I know the T2 has a fuel pump relay for low and high load, but this t2 engine is in a NA shell so was i not running full voltage to the fuel pump anyway? Other symptoms the exhaust smells like gas and is a little smokey and it occasionally backfires while trying to start. I'm searching high and low for vacuum leaks. I have removed all emissions so there's not much too search. I checked resistance in both leading and trailinig coils and they both were within FSM specified values (0.4 ohm exactly). I pulled the almost brand new spark plugs and they were dark with carbon and had droplets of unburnt gas on them. Is having the fuel pump wired like this causing a "too rich to start" condition? What could cause the fuel pump to see no voltage so suddenly while driving? Is this somehow a result of the faulty MSD unit? I have a spare set of bur9eqp NGK's which I am currently running in both leading and trailing positions. I want to to try to start it with the new plugs but if its so rich why foul them? Right? Thanks for reading and any helpful input is much appreciated!
SO... I wired a 4 pin relay and fancy toggle switch below the dash and have the fuel pump (255lph Walbro) connected directly to the battery from the relay/switch and there is battery voltage at the pump, but the car hasn't started since. So is it possible I am dumping a ton of fuel, too much for the start map on the factory t2 ecu? I ran the battery out and after letting it charge a while (jumpered with the trusty corolla), it was fully juiced and perhaps the starter spun fast enough to skip the start map causing it to fire up but run terribly, is this scenario possible? At this point i should have messed with the safc2 to see if it could help improve idle/ low rmp but it ran so boggy i wanted to scream and cry so instead I let it sputter out. I know the T2 has a fuel pump relay for low and high load, but this t2 engine is in a NA shell so was i not running full voltage to the fuel pump anyway? Other symptoms the exhaust smells like gas and is a little smokey and it occasionally backfires while trying to start. I'm searching high and low for vacuum leaks. I have removed all emissions so there's not much too search. I checked resistance in both leading and trailinig coils and they both were within FSM specified values (0.4 ohm exactly). I pulled the almost brand new spark plugs and they were dark with carbon and had droplets of unburnt gas on them. Is having the fuel pump wired like this causing a "too rich to start" condition? What could cause the fuel pump to see no voltage so suddenly while driving? Is this somehow a result of the faulty MSD unit? I have a spare set of bur9eqp NGK's which I am currently running in both leading and trailing positions. I want to to try to start it with the new plugs but if its so rich why foul them? Right? Thanks for reading and any helpful input is much appreciated!
Last edited by mattfromthepier; 04-25-18 at 11:37 AM. Reason: specify series 4 swap and series 4 chassis
05-30-18, 02:41 PM
#2
I'm not too well-read on the Rtek ECUs aside from them being modified stock ones with features similar to the Apexi PowerFC, but I have a feeling that it was not tuned correctly before.
750cc primaries flow ~36% more than the stock 550s, so EVERY fuel map would have to be tuned to compensate in order to yield the same amount of fuel delivered (reduce injector time by 36%). I'm not the most well-versed person in tuning, so this question would best be placed in the Standalone EMS section.
As for your Walbro pump, the car doesn't care. The fuel pressure regulator is what makes it behave. As long as there's enough fuel being delivered, the FPR will send any extra back to the tank. I've run both a stock FC pump and a FD pump in Project OldTree before the 20B met the car (stock s4 GXL with Taurus alternator/fan). Car behaved the same no matter what. With the 20B, all I did was wire the haltech's fuel pump relay output into the stock power feed to the pump. Having a slowdown resistor on the fuel pump seems kind of silly to me anyway...
Why are you running four BUR9EQP plugs? For leading plugs on a Rtek'ed ECU and stock turbo, this sounds like a recipe for fouling as the BUR9EQ's are two ranges colder (plugs pull more heat out of the engine).
To be honest, this car NEEDS a wideband. Based on the amount of mods done, it sounds like a haphazard build because it is running excessively rich and any attempt to tune via the SAFC2 means you're making adjustments blindly. This can go bad and quickly if it goes lean in boost... BOOM
I encountered the same behavior (car falling on face) on Project OldTree right after I got the 20B running, and it showed up clear as day on the Haltech's datalog. It displayed my AFR in the 12-13 range, then jumping to 15-17 all of a sudden when the car would fall on its face. While driving, it showed the same on my Innovate LC1's gauge too. After some back & forth with J9FD3S, we determined that it was running extremely rich and the accumulated extra fuel was passing over the WBO2 sensor every so often, which can't see unburnt fuel, making it appear lean. Leaned out the map in these areas to ~13.5 and most of the AFR spikes disappeared. This was in vacuum. When the car finally got to see boost, it behaved the same way. Lean it out to 13.5 and she immediately drove better. Eventually, I had a decent running tune up to about 6000rpm in 3rd gear.
Mind you, this is with stock 550/550 injectors, so my injector pulse time would be different than yours. Either way, a wideband is the right tool for correcting this issue. There's a LC1 on ebay right now for $50, just needs a fresh sensor. it's a LSU4.2 sensor, found on a bunch of Volkswagens (any 01-05 beetles, Bosch #17351 or #17085)
750cc primaries flow ~36% more than the stock 550s, so EVERY fuel map would have to be tuned to compensate in order to yield the same amount of fuel delivered (reduce injector time by 36%). I'm not the most well-versed person in tuning, so this question would best be placed in the Standalone EMS section.
As for your Walbro pump, the car doesn't care. The fuel pressure regulator is what makes it behave. As long as there's enough fuel being delivered, the FPR will send any extra back to the tank. I've run both a stock FC pump and a FD pump in Project OldTree before the 20B met the car (stock s4 GXL with Taurus alternator/fan). Car behaved the same no matter what. With the 20B, all I did was wire the haltech's fuel pump relay output into the stock power feed to the pump. Having a slowdown resistor on the fuel pump seems kind of silly to me anyway...
Why are you running four BUR9EQP plugs? For leading plugs on a Rtek'ed ECU and stock turbo, this sounds like a recipe for fouling as the BUR9EQ's are two ranges colder (plugs pull more heat out of the engine).
To be honest, this car NEEDS a wideband. Based on the amount of mods done, it sounds like a haphazard build because it is running excessively rich and any attempt to tune via the SAFC2 means you're making adjustments blindly. This can go bad and quickly if it goes lean in boost... BOOM
I encountered the same behavior (car falling on face) on Project OldTree right after I got the 20B running, and it showed up clear as day on the Haltech's datalog. It displayed my AFR in the 12-13 range, then jumping to 15-17 all of a sudden when the car would fall on its face. While driving, it showed the same on my Innovate LC1's gauge too. After some back & forth with J9FD3S, we determined that it was running extremely rich and the accumulated extra fuel was passing over the WBO2 sensor every so often, which can't see unburnt fuel, making it appear lean. Leaned out the map in these areas to ~13.5 and most of the AFR spikes disappeared. This was in vacuum. When the car finally got to see boost, it behaved the same way. Lean it out to 13.5 and she immediately drove better. Eventually, I had a decent running tune up to about 6000rpm in 3rd gear.
Mind you, this is with stock 550/550 injectors, so my injector pulse time would be different than yours. Either way, a wideband is the right tool for correcting this issue. There's a LC1 on ebay right now for $50, just needs a fresh sensor. it's a LSU4.2 sensor, found on a bunch of Volkswagens (any 01-05 beetles, Bosch #17351 or #17085)
07-26-18, 08:39 PM
#3
mattfromthepier
Thread Starter
Thank you for the reply! There is a Innovate MTX-L installed, no longer working as the sensor is likely fouled from... running rich haha. It worked for a short time, and the afrs under load were proper rich as I recall high 11's, and I only used the safc2 to make adjustments at idle, nothing more. But adding to my previously saved reply I have found the culprit.... it was the egi comp fuse 
. In just the right light with a high powered flashlight I could see just a spec of what looked like corrosion. I switched it with the 30 year old 30amp headlight fuse and it fired right up! Oh man, what a relief! These are tears of happiness haha Thank you again for your reply and advice Akagis White Comet, I greatly appreciate it! Cheers!
. In just the right light with a high powered flashlight I could see just a spec of what looked like corrosion. I switched it with the 30 year old 30amp headlight fuse and it fired right up! Oh man, what a relief! These are tears of happiness haha Thank you again for your reply and advice Akagis White Comet, I greatly appreciate it! Cheers!
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