Air fuel ratios

Hi, friends.

I finally installed the LC Engineering low-boost (70mm) supercharger on my 1997 3RZ-FE.

My truck includes the OEM ECU, LC Engineering street headers, Magnaflow catalytic converter, LC Engineering cat-back, K&N FIPK cold air intake, 1" throttle body spacer, OEM injectors, OEM fuel pressure regulator, OEM fuel pump, new fuel filter, and 92 octane fuel.

I have driven approximately 200 miles with this new supercharger.

I have not pushed it too hard. I have brought it up to 3.3 pounds of boost maximum, and only about 3.3K RPM. Since I have not brought the truck up to ~5.5K RPM (redline) it is hard to say how much boost it will actually make.

I realize this is a nebulous, idiosyncratic question but, nonetheless, I want to know what air-fuel ratios you all target (or avoid) in certain scenarios, i.e. wide-open-throttle, idle, cruise, etc. That being said, I apologize if this question is frustrating but anecdotes in this context are, to me, actually helpful.

 

For posterity, this is what the truck sounds like: https://www.youtube.com/shorts/cc2PI4QyXoY

 

Lean conditions aren't as bad for it at part throttle as WOT. It's really WOT near redline you have to have your AFRs dialed in pretty close (12:5ish). Part throttle lean you might get some pinging, but probably not with 92 octane and a good 6 or 7 heat range plug.

 

I use NGK iridium spark plugs. They were the nicest ones I could find for my truck. I hope they are sufficient from a heat POV.

Like mentioned in my OP, I haven't taken the truck to redline. I am a little afraid of doing so but I will bring the engine up to temperature and see what happens soon.

 

bkr6 or bkr7 heat range is what you're looking for. although I've run stock 5 range heat plugs and didn't notice any problems.

 

I have ik20 in my 5vz sc. After driving for a while you can pull plugs and see if you need to go up or down in heat range. At WOT or high loads you want to see lower than 14.7 to 1. Above 3 psi I would try to stay around 12.5-13 to 1. Part throttle or light cruising it's okay to see it lean out for fuel economy. What you want to avoid is being in boost and lean. Rich is safe. The big problem is because there is no intercooler your temps will get really hot and can cause knock. That's why a lot of people like water/meth to help keep temps cool.

 

I went driving tonight and I brought it up to 5.5K RPM.

The supercharger kept maxing out at 3 to 3.5 pounds of boost.

To be honest, I am a little frustrated. My engine is noticeably stronger but not as much as I hoped.

Anyway, I noticed that at about 60-65 MPH in fourth gear on hills, the truck would dip into the 10 AFR range at 3 pounds of boost.

When cruising on the highway, boost remained mostly negative unless I accelerated. Then, it would go into boost at around 1-1.5 pounds with an AFR of around 13.

I am a little surprised to hear you think water/meth would help with such low boost numbers; however, that is something I debated early on.

 

So, I adjusted the stopper bolt (not sure what else to call it) on the bypass valve a few turns counter-clockwise.

I also discovered that my mechanic accidentally swapped the orientation on my oil separator can, so I fixed that.

I went for a drive. At wide open throttle in third gear at somewhere around 3 to 3.5K RPM, I reached 4 PSI

I should also add that the truck felt more responsive and speedy than before.

I need to test the truck again on the highway but these results seem a lot better.

 

10 on the AFR gauge is where mine maxes on the low side, so it may be richer than that. Get your AFR up to 12.5 at such a low boost setting and it'll be a lot stronger. You're losing a lot of power being so rich.

 

I'm way too familiar with that SC on a 95-97 4 banger.... during pulls and little accelerations around town start watching your ignition advance too. I'd bet it is tanking and pulling a ton of advance out. FWIW 10AFR is really low under your boost level but not enough to really be killing your power, just not making as much as it could (probably around 5-8hp less)

 

This is my first project vehicle.

I lived in NYC for most of my adulthood so I couldn’t have a car at all.

I am learning.

What can I do to fix the issues you two mentioned above?

 

I don't have a great recommendation for correcting the low AFR except to say it isn't really a concern either. The AFR you should be concerned with isn't wide open throttle (open loop) it is the partial throttle boost AFR (closed loop). That's usually where the stock ECU leans out a bit too much and ping occurs and causes the ECU to pull timing making it feel sluggish despite the boost. That's why I'd recommend having an UltraGauge so you can watch your open/close loop status, timing advance, fuel trims, and MAF flow all in one screen. The ultimate solution is an aftermarket ECU, then you can put the really tiny pulley on and spin that thing up. But right now monitoring and learning to drive around the weird behavior will help a lot. I had that SC on my last truck, it wasn't a bad experience but it costs a lot more to make it a great one ya know?

 

Something I have always wondered: do all aftermarket systems require rewiring the truck?

I would not mind rebuilding the engine bay wiring harness; however, rewiring everything seems like a gargantuan task.

 

Nope, I just ordered an adapter harness from Boomslang for my truck, plugged right from the stock harness into my Haltech Elite. I did do some modifications to my harness afterwards to add some functionality.

 

I have a lot to learn. I have so many questions. e.g. Does this delete the stock ECU? Are folks drilling through the firewall to accommodate the extra wiring? I need to dig around and find some high-quality threads around here.

 

This requires no drilling and it completely replaces the stock ECU. My build shows it a bit and the haltech discussion thread has information about it as well (although its more about the actual tuning).

1st Gen Haltech ECU Discussion

 

Thanks, @Speedytech7.

 

How much did the adapter harness and haltech cost you? Snp sells adapter kits but that price tag makes me reconsider...

 

Adapter from Boomslang is around $500 and the haltech was $1100 on sale. I also got the wideband CAN module too for another $250 on sale.