General questions re: old Greddy kit
Howdy,
New to Miata's, not to forced induction. Just picked up a 1992, 1.6 obviously, with a TD04-15. Runs, and drives, albeit with a litany of niggling issues. Mods that I know of: TD04 turbo cast manifold of some sort (w/ relief cuts) upgraded fuel pump (indicated by independent wiring/30 amp relay wired inline) RX7 550cc injectors RX7 AFM Bosch 710 diverter valve Stock FPR (apparently) oil cooler (GM type, coolant operated) Stock ECU So, the main problem I'm having at this point relates to fueling. I'm in the process of acquiring and installing an AEM wideband, in a secondary bung, so I can actually see real AFR data. For now, it's running a shitty little autometer gauge off of the narrowband output. Not enough data to extrapolate numbers, but enough to know that I'm running quite rich up top (4,500RPM+, 10lbs boost). Runs rich enough to choke on itself half the time. No indication of leaning out nor knocking, in fact, quite the opposite. I enjoy the level of safety, but washing down the walls is not good, either. Additionally, I'm blowing oil out the back of the valve cover, not enough to affect level, but enough to drip on the downpipe and make a bit of smoke when driven hard and stopped. There's a PCV in the stock location, running to the intake mani, and a PCV inline between the driver's side of the valve cover and the pre-AFM part of the intake. At idle, it varies between 14-18inhg vacuum, while it's around 22inhg when coasting with the throttle closed. I'm thinking this may be a PCV problem, and considering running a catch can to ameliorate it. Anyone have any ideas on the fueling? My next step was to install a wideband and start soldering resistors into the AFM. I'm at a loss. If I end up having to go megasquirt, I'll do so, but if I can put that 800 dollars to use elsewhere, I'd rather do that. I just don't know enough about the fueling on these cars to know if the pump and injector upgrades are adequate in the absence of an adjustable FPR. Halp |
you've probably washed the cylinders down so much with gasoline that oil can now freely make way past rings...
if you're running a stock ECU then you need stock injectors and AFM. there is no level of safety with your setup. |
Originally Posted by Braineack
(Post 1388404)
you've probably washed the cylinders down so much with gasoline that oil can now freely make way past rings...
if you're running a stock ECU then you need stock injectors and AFM. there is no level of safety with your setup. So, assuming that the rings aren't completely done for, next step has to be a piggyback, or full MS, correct? |
Only two oil seals on back of valve cover I'm aware of are the valve cover itself and the CAS seal. EDIT: I meant to add that I'm uncertain if fixing the PCV issue will fix that, or if the seal is just bad from adjusting timing.
I believe most will agree that the megasquirt would be a high priority; I'm just not certain if they would put it, or the 1.8 swap first in line. If the engine is roached, that will clear up the priority list in a real hurry. The stock ECU has no provision for running injectors that size- that is your problem. |
Originally Posted by Asulen
(Post 1388407)
Only two oil seals on back of valve cover I'm aware of are the valve cover itself and the CAS seal.
I believe most will agree that the megasquirt would be a high priority; I'm just not certain if they would put it, or the 1.8 swap first in line. If the engine is roached, that will clear up the priority list in a real hurry. The stock ECU has no provision for running injectors that size- that is your problem. I guess I gotta compression test it and see where the bottom end is at. I have 2 other vehicles, so if it comes to the point of needing a new engine, I'll probably just throw it on a back burner for a year or two until I have the funds to do it properly. If the compression is a bit low, but within spec, I'd probably just leave it be. It doesn't need to be mint, again, it's sort of a fun toy car, but if the cylinders are over 25psi out of line with one another, I guess I know what I gotta do. |
problem: The ECU goes into open loop at ~5.5K + you have double the stock injector size + you're increasing fuel pressure.
Solution: remove the fuel pump. remove the FMU (im assuming this kit has the Blue Vortech FMU?). remove the AFM. remove the stock. install an aftermarket ecu that can actually control the injectors AND spark timing. in the least you need to swap out the 12:1 ratio FMU diaphragm for something around 4:1. |
Originally Posted by Braineack
(Post 1388412)
problem: The ECU goes into open loop at ~5.5K + you have double the stock injector size + you're increasing fuel pressure.
Solution: remove the fuel pump. remove the FMU (im assuming this kit has the Blue Vortech FMU?). remove the AFM. remove the stock. install an aftermarket ecu that can actually control the injectors AND spark timing. in the least you need to swap out the 12:1 ratio FMU diaphragm for something around 4:1. |
Pics Pics Pics! They always help!
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Originally Posted by Jack Straw
(Post 1388415)
That's the strange thing: under the hood, there doesn't appear to be any sort of FMU, in fact, it appears to be the stock system. I'm probably gonna pull it all apart, there's a hairline crack in the exhaust mani which I need to braze. Would that FMU with that disc be at least a temporary fix?
I'm curious what your AFRs at idle are even at. The stock ecu, even in closed loop with a larger tinkered with AFM, still can't really trim the PW enough (batch injection makes it that much harder). Then when you hit open-loop at 5K, and the fuel map dumps in a shit ton of fuel I'm surprising youre not getting spark blowout and bogging. this is what AFRs look like when the stock ecu idles 550cc injectors: https://www.youtube.com/watch?v=yuyQLsmEHqQ |
3 Attachment(s)
Originally Posted by Braineack
(Post 1388433)
The GReddy kit was shipped with a Vortech FMU with a 12:1 ratio disc -- it was good for getting the fuel pressure up to +100psi with boost so the stock injectors could adequately fuel 5-6psi. Since you have double the injector, you don't need much extra fuel pressure, if any at all, to provide enough fuel when in boost. 550cc injectors can fuel over 250rwhp on a stock fuel system.
I'm curious what your AFRs at idle are even at. The stock ecu, even in closed loop with a larger tinkered with AFM, still can't really trim the PW enough (batch injection makes it that much harder). Then when you hit open-loop at 5K, and the fuel map dumps in a shit ton of fuel I'm surprising youre not getting spark blowout and bogging. this is what AFRs look like when the stock ecu idles 550cc injectors: https://www.youtube.com/watch?v=yuyQLsmEHqQ That's exactly what I'm trying to say re: choking, it's experiencing bogging and spark blowout at 5,000+. Here are a few pictures, no FMU to be seen. I took a couple videos of the idle, haven't uploaded them yet, but it is kinda lopey, sort of like a cam, but moreso due to the stock ECU trying to keep it stoich and bouncing around miserably. It's a reliable idle though, I have it set right around 950-1000, so it doesn't stutter when loaded at idle. |
Purchased the aluminum Moroso separator from Moss, and a 323GTX PCV valve from Treasure Coast. Hopefully helps some of the oil burning. I wasn't gonna replace the valve cover gasket until I solve the crankcase pressure issue, of course.
Question re: the routing. There's the PCV valve in the stock location, between the intake mani and the PS of valve cover. And there's one between the DS of valve cover and the pre-turbo, post AFM side of the intake. I figured I could cap the intake mani, run the separator off of the PS and DS of the valve cover, with a T fitting between them and the separator, and run the outlet for the separator with the second PCV up to the pre-turbo intake pipe. Sound about right? EDIT: I see how Moroso outlines it, installing it on the PS firewall routed between the intake mani and PS VC. In theory, this shouldn't be a problem with a PCV valve which stays closed under boost. But, I'd rather not have the intake mani involved at all; I can pull permanent vacuum from the pre-turbo intake pipe. Idk, help y'all. |
If it were me, I'd put stock injectors back in with a vortech FMU, or get spark/fuel management.
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Originally Posted by Jack Straw
(Post 1388529)
That's exactly what I'm trying to say re: choking, it's experiencing bogging and spark blowout at 5,000+..
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Originally Posted by Braineack
(Post 1389791)
If it were me, I'd put stock injectors back in with a vortech FMU, or get spark/fuel management.
Originally Posted by ryansmoneypit
(Post 1389795)
Previous owner must have been a Buddhist Monk. No regular everyday dude could have the patients to drive a Miata that sputtered at 5k, for 40,000 miles.
The possibility of building a MS or even rewiring/changing resistors in the stock AFM as a temporary measure isn't entirely off the table. |
if you are building an ms.. then just get rid of the afm all together and run MAP and retune for the 550 injectors. the pump and 550 is overkill for the stock ecu to handle.. i believe the 1.6 ecu could only handle up to 305cc.
direct replacement from a supra 89-92 non turbo 7mge with light green top injector number 23250-70080 |
it can only "handle" them in the fact that the motor doesn't get completely flooded...
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Originally Posted by asianalpha
(Post 1393406)
if you are building an ms.. then just get rid of the afm all together and run MAP and retune for the 550 injectors. the pump and 550 is overkill for the stock ecu to handle.. i believe the 1.6 ecu could only handle up to 305cc.
direct replacement from a supra 89-92 non turbo 7mge with light green top injector number 23250-70080
Originally Posted by Braineack
(Post 1393409)
it can only "handle" them in the fact that the motor doesn't get completely flooded...
So, guys, I did some normal wear items, specifically plugs and wires (NGK blues to Bosch BKR7E iridiums) and replaced a few couplers with stuff from my friend's aircraft shop, and, lo and behold, it runs like a champ. I have no idea what kind of black magic is occurring under this hood, but it idles fine, still fluctuates a bit, probably a shot injector O-ring, as I ruled out any other vac leaks, and the boost is controlled in quite the ghetto fashion, with a helper spring from the wastegate bracket. It's showing 11-12psi now, pulls hard, gonna leave it be for a while until I can shell out for a proper MS build. From all of my other reading, you're all right, it shouldn't even be able to idle these injectors on a stock ECU. There's no aftermarket control of which I'm aware. So, idk, what's going on, but it's working, screw it. Thanks for the help, y'all. |
what are your AFRs?
No one is questioning the fact that you're actually idling and driving on them, the problem is, the ECU can't adequately reduce the PW small enough for an injector more than double the stock size. if you really want your miata to pull hard, you'd actually set it up so it didn't run like absolutely trash, fuel wash the clyinder wall, and make no more than 8mpg. I bet you're only making 150rwhp... |
Originally Posted by Braineack
(Post 1397011)
what are your AFRs?
No one is questioning the fact that you're actually idling and driving on them, the problem is, the ECU can't adequately reduce the PW small enough for an injector more than double the stock size. if you really want your miata to pull hard, you'd actually set it up so it didn't run like absolutely trash, fuel wash the clyinder wall, and make no more than 8mpg. I bet you're only making 150rwhp... This isn't my first rodeo, so I know there is truth to what you're saying. But, I don't have the same income as I did when I built my last two vehicles, and also have two other vehicles to maintain, 36k college tuition, full time job, etc etc etc. That said, assuming I got a wideband and welded a separate bung in a more friendly location, so I had a baseline way to estimate tweaks, what would be YOUR, the guru's suggestion, regarding the most cost effective, dollars-per-horsepower solution to this shit show of a vehicle? Would the FPR/FMU and 305's be the ticket? I believe it has a 190 in the back, definitely not stock pump - 30A relay inline from battery. Thanks. |
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