Lean isn't the issue it is the 2 to 3 lamba bounce I get at cruise that I worry about and I am trying to fix.

bouncing between what and what? (in afr please, when did we start talking about lambda?)

bounce from 12.0 to 16.0

There's your problem

Except that walbro's, whinboros', walsucks, wilpuke, all those pumps are HORRIBLE pieces of crap. I wouldn't trust one on an n/a car. Garbage

You don't understand Lambda, do you?

We can't be, mathematically a 2-3 lambda bouce would be 29-43:1

That's AFR's, not Lambda. Lambda = actual AFR/14.7

I mixed the two up it is my mistake. I meant AFR.

So what is the answer then? what type of fuel pump should I use?

Indeed TTT, do tell... Is your disdain for Walbro pumps your way of saying this sounds like pump failure or more along the lines of an endorsement for some uber expensive alternative that you prefer?

Rick, did you ever figure out what injectors you're running? Having the wrong presets selected probably wouldn't make for the best running conditions.

afr swings at cruise are most likely attributed to the ecu falling in and out of closed loop... or not even reaching closed loop... and that could be to a variety of reasons.

Almost none of those reasons would have to do with fuel pressure. Are you running a stock 1-wire O2 for the stock ecu? If not, are you using the simulated 0-1 volt out on your wideband to the O2 input on the ecu? Have you made any adjustments to the cruise area of the map where it is now too lean and causing hesitation? If your ecu even reaching closed loop mode?

I don't think you are looking in the right place to fix your problem. These ecus were designed to work in a stock capacity with stock components... Its very easy to make a change that the ecu cannot compensate for, or even knows about. Yes these are old ecus with old technology, but the technology worked for many years before people started modifying them.

I beileve that they are 720's if I change the computer to anything else it is scary.

when I 1st posted this I was directed to another thread on the evil fourm that stated a few people had the same issue and their fix was to replace the FPR and turn up the pressure a little. I also read in street rotary that running a high fuel pressure could help to atomize the fuel better.

it is a narrow output from the wideband. I haven't driven the car with the pda hooked up in a while. However the AFR will bounce inbetween 2,500 to 3,500 Rpm with low vaccum. When I get on in even into boost the AFR will stay pretty steady.

Whoops... forgot to mention what I thought the original issue was.... I'm voting TPS.

If it's not pump failure it will be soon

My ubber expensive hella reliable badass pump that I use in my own car is a stock supra TT pump ;)

I've driven this car and there doesn't even seem to be anything wrong. Honestly, there were no complaints about how it drove before he installed the wideband, but now that there are numbers that change, there must be an issue. My honest opinion is that this is more a case of observation bais than anything else. But what is being observed is most likely what you're referring to. In cruise I see 14.5-16 afr and under light to moderate acceleration it dips down to 12's and 13's....nothing special there.


The Rtek 2.1 has the capacity to adjust fuel and timing so its certainly more flexible than the stock ecu....for example the ability to datalog. Rick take some logs and post them and point out exactly where the problem is occuring. Doing so will allow you/us to see what the TPS value, inj duty cycle, afr and other parameters are and allow us to do more than guess at what the problem is.

quite possibly

Hard to beat OEM for reliability. I got rid of my walbro (came installed on the car when I got it) and installed an FD pump because 1) it was loud as hell and 2) it caused the car (otherwise completely stock) to run rich, smoke on start up and occasionally not want to hot start.

The car also has issues idling after 1st start up it will be fine after a few mintues of driving but it will sometimes drop really low when I put the clutch in for a stop. It will die in the 1st 5 mins of driving.

Also my logs will only be with narrow band inputs I haven't wired it up for datalogging yet

I have some logs but I am not sure how to share them.