Running rich.

[Dan_Gyoba]

Like really rich.

I know that the 7M-GTE isn't known for it's lean tastes, but I think that this is getting to be a bit much...

Okay, when I installed the HKS SSQV, I expected that it'd start running rich at shifts. I got the occasional backfire in the exhaust, more so when the car was cold, or at least in open loop mode, or when there was a big dump through the BOV (Both open loop AND a lot of metered air escaping)

Well, I installed the big turbo, but I've got the SSQV recirculated now, and I've started getting those backfires again, sometimes when I'm barely even letting the BOV open. In addition, my fuel economy has spirelled into the ground of late.

So...

Troubleshooting: Things that hace occured to me.

If the O2 sensor were to go, shouldn't the ECU be throwing codes? Could I just have carbon fouled it when I installed the BOV, and now it's getting worse?

What are the symptoms of leaking injectors? Is the Cold Start injector possibly suspect?

My IC piping is, admittedly something of a mess, and there is certainly the possibility of a leak, however, the car also seems to be running rich when I'm not under boost. Now the intake piping before the manifold is going to be under higher pressure than the manifold, so it's possible that I'm still leaking from there somewhere.

Anything that I've missed?

I'm a bit shy on cash at the moment, so I'd like to spend my repair/maintenance money as wisely as possible.

O2 sensor: If this is the case (It MIGHT fail but not throw codes) then replacement of the sensor is most likely the correct course of action.

Injectors/CSI. I take it here, the injectors can't be repaired, they'd need to be replaced. The injectors are the PTE ones, I'd hope that these are unlikely to leak. If they need to be replaced, I'd figure that it'd be best to replace all 6. The CSI would be the best case scenario here, where it at least is all by its lonesome.

Intercooler piping: Well, I need to do something about this anyway. Glen has indicated that he could fab up something for me, of course that's time and money dependant. He's got to have the time to do it, and I've got to have the money to pay him for it. ;) Maybe I should get a cheap boost gauge and see what the pressure in the intake piping is like...

[Keros]

I'll lend you my boost leak tester for a bag of jelly beans.

It's made out of an electrical conduit and essentially replaces the stock AFM on the accordion hose. It has a standard 1/4" compressor fitting, isolation valve, and a gauge.

My intercooler pipes may look like ass, but it doesn't leak a molecule.

The advantage of course is that should you have a leak at the throttle body or intake manifold, welding the pipes as a "throw parts and money at it" solution will not fix it. The boost leak tester will find any leak in the system with alot of hissing and the gauge dropping.

[Dan_Gyoba]

Thanks for the offer, but I'm not sure that I can use it as is, since I have a Lexus AFM.

Also... How does that work with the PCV? The TB should have a one-way check valve, but the accordian hose side will be a leak, from which you'll be pressurising the crankcase...

[Keros]

If you have a stock accordion hose, it will work as that the afm must be removed from the car (the tester goes where the AFM usually is). I can't find a picture of it right now, but I know I took one a while ago... anyway, I adapted it to work on a Dodge Daytona with a few parts from Home Depot and Canadian Tire. If you don't have the stock accordion hose and use some other arrangement, you'll just need to figure out an adaptor to make the two sizes work. An inner tube and some good adhesive might work. Mounted on my car it can only hold 10psi before it pops off the accordion hose, sometimes violently, lol.

I don't have a supra or the tester to take pictures of right now either (it's in airdrie, I'm not ;) )... regardless, I'm sure a chap as resourceful as you could make it work. The stock accordion hose is just the right size to fit the mouth of the tester. If yours is stretched a bit, you may need a piece of rubber or something to make it a snug fit.

Yes, it will test the PCV system by pressurizing it from the back. Any part of the intake that isn't isolated by valves will be pressurized. The hoses that run to the charcoal canister will have to be blocked off when the AFM is removed (stock configuration has a few steel pipes on the AFM's mount that are part of the vacuum system). In any case, you'll know where the leaks are because even the tiniest crack moves enough air to be audiable. Some soapy water in a windex bottle makes a good sniffer.

The tester works on the principle that you are replacing the air filter with a giant plug... a plug with a compressor fitting in it. The air filter should be the only way for air to enter the intake and the valves should be the only way that air should be able to leave. IIRC, there's no valve overlap on the 7M, so if intake valves are open, the exhaust are closed and vice versa. There should be no leaks, anywhere, if the air filter is blocked and the system pressurized, engine off. Using the tester in place of the AFM and attached to the accordion hose, everything that is a part of the intake system will be pressurized, the pcv, the charcoal canister, the boost gauge, the intake side of the head (if you hear a leak out the exhaust, you have a bad valve somewhere). The throttle plate isn't a perfect seal, so even everything beyond that will see pressure. It's the most thorough intake system diagnostic I know of ;) If there's a leak, it'll find it.

[uncorkedsupra]

i read somewhere that the cold start injector is prone to leaking on these beasts. it could be something you may want to check?

[Dan_Gyoba]

Keros: I'll have to maky my own tester though, since a stock accordian hose will never fit on my turbo. The turbo's got a 4" inlet, so I had to do fabricate a replacement for the part. I understand the concept, and as long as I'm not going to be pressurising the crankcase, (Which is really bad for allt hose brand new seals that I have in there) Ill give it a try, though I really DO want to get better IC pipes done up.

I don't have the stock AFM mounting bracket with the charcoal cannister hose parts anymore, it wouldn't fit where I have to have the AFM with my cobbled together accordian hose replacement.

Thanks for the offer, but I'll have to get something else figured out.

[Bri-Guy]

Wish that I was rich..... That is all that I have to say.


Don't want to ruin a good discussion. Looks like you are on the right track Dan, testing for leaks, then the CSI and then possibly the injectors (least likely IMHO). I haven't hear of any other usual suspects that would be worth checking into.

As always, keep checking with the cheapest/easiest/ most likely sources of issues to get it figured out.

Your recent mileage issue could also be related to the additional cold and snow we've had. Additional warmup, idling in traffic (minor contributor) slow moving traffic moving in a low gear and such, maybe.

I'm sure that others will post up their suggestions about how to investigate solve this problem, be sure to keep us in the loop on how this gets resolved.

Also the PCV should be one way from the crankcase to the intake or otherwise we'd all have issues when creating boost on the intake side. Pressurizing the intake side and plugging the appropriate vacuum lines should work no problem for looking for leaks.

[Bri-Guy]

Nevermind my boost comment about the PCV. The PCV should route back to the intake side pre-compressor if I think about it. So boost has no impact, but the v alve is still one way to vent the crankcase.

[Funkycheeze]

I'd check for a boost leak first - smoke testing works well

Then i'd do a fuel pressure check - make sure it is within the factory spec, and doesnt drop off really fast when the engine is turned off (meaning leaky injector)

If still no dice, probably a bad 02 sensor or ECU

[annoyingrob]

Also check the wiring to the coolant temperature sensor. If it has a bad connection, the car will dump in more fuel.

[Funkycheeze]

It would also read dead cold on the cluster

[annoyingrob]

No it wouldn't. The gauge uses a different sensor than the ECU.

[Funkycheeze]

on the 7m?

i dunno man - i'll check tomorrow

[suprago]

EWD(1990) reports an EFI water temp sensor and also a water temp sender.

[Dan_Gyoba]

I'll have to check that. I messed with the gauge temp sender and now my gauge does a funky dance now and again. Gotta fix that... I noticed also that my turbo water return is leaking a bit. Actually that's kind of a relief, since now I know where my coolant is going. I had thought that it was the heater core.

[hurricanehyshka]

have you noticed any change in power?

[Dan_Gyoba]

Well, I haven't exactly been driving around wiht my foot on the floor with current road conditions, so no... I haven't noticed, but that doesn't necessarily mean that there isn't a change.

[hurricanehyshka]

very true about the weather!! have you ruled out ignition problems and electrical components? maybe its just spark plugs not burning off fuel? maybe its the cold weather and your ecu is dumping more fuel to compensate dense air?

[Dan_Gyoba]

The ECU should compensate correctly for the cold air, and the engine is running pretty smooth, so I'd figure that the spark polugs should be fine. (The plugs are new OEM plugs as of last summer, so they'd better be good!)

Of course the coils are a bit of an unknown, but I can't see why things would have changed. I'll look into that, too.

So far though, O2 sensor and boost leaks are my lead candidates.

[celica83_gts]

I've killed O2 sensors with rich mixtures. They don't fail completely, but rather tend to "poop out", not reaching their peak voltage output. If that's the case here, the ECU will keep adding fuel, trying to bring up the signal voltage. I'd try a good sensor, reset the ECU, and see what happens.

[annoyingrob]

Edit: wrong thread.

[Dan_Gyoba]

@Bob: That's the kind of information that seems to make sense here. I still want to check against a boost leak though. I think I'll see about putting a boost gauge in the iC piping to see if a boost leak could cause the problem though. It shouldn't if the intake is in vacuum though.