doug 88 s4

I had my 88 s4 5spd dynoed last week with great results 322.34 hp and 312.34 torque. Over the past couple of years I have added headers, removed cats, added a RMB, plus chipped it and installed a stage 1 vortech SC. The air/ fuel ratio is lean (14.5/1). Any suggestions on how to increase the fuel.

Doug

mark kibort

chip mods or RRFR. 14.5 is EXTREMELY dangerous. great for cruising, but under WOT conditions, and a certain % of max output for the engine, you can poke holes in pistons.

mk

doug 88 s4

Sorry I don't know what RRFR or WOT means. Also, any thoughts on how to increase the fuel.

dprantl

Anything above 13.2:1 and I would be VERY nervous. An RRFPR is a Rising Rate Fuel Pressure Regulator. It allows you to adjust the fuel pressure. WOT is Wide Open Throttle, and if your WOT switch is not working, the LH brain will not know to switch to the WOT map from the cruise map and the car will try to run in closed-loop mode with the O2 sensor keeping the AFR around 14.7:1.

First check that your WOT switch is working. It is mounted to the side throttle body. If that checks out, the best remedy is to have a set of custom fueling chips made for your car.

Dan
'91 928GT S/C 475hp/460lb.ft

Vlocity

I have a Kenne Bell fuel management unit that would solve your problem. It is used but in very good condition. I also have a complete rebuild kit for it new in the bag. $125 for both.

Here's a link. http://www.bellengineering.net/produ...&products_id=1

In addition I have a set of 30# injectors that have less than 2000 miles on them. $150 for the set.


You need to be at 12-1 AFR.

I wouldn't drive the car until it's fixed.


Regards,

Ken

Z

By far, the most likely problem is that your full throttle switch isn't working.

doug 88 s4

Ok Ken,
I looked up your Bell managment system. If I buy the rebuilt one what else do I need to do. How will I know when i am running 12-1

928autobahndreamer

Are you sure that things are running well? I would expect an 88 S4 5 speed with headers, no cats, and a Vortech supercharger to be putting down a Lot more than 322 RWHP. A stage 1 Murph kit should put down 400RWHP.

Tim Murphy

I talked with Doug and he is going to check out a number of things that could be causing problems.

322HP is very low for a Murf 298 stage one kit but because he is only 322 he is most likely still in the safe area with 14.5:1 AFR and the stock timing retard capabilities of the stock configuration.

His car is a euro car so that does change a few things. I send out an EZK chip with the Stage One kit and there is a chance that he is not running with that chip but he is going to look into it. He mentioned that he is running performance chips that he bought off Ebay and that may (or may not) be the root of of his issues. The Murf 928 Stage One chip is only modified to pull timing out under WOT and is setup for USA cars so it may not even take effect with his car (didn't know his car was a euro). I can set it up to run with his configuration but that is not the way it currently is. This has nothing to do with AFR or the low HP numbers.. We will figure it out.

BTW, no offense to Ken, do not run the Corky Bell FMU, use the one sent with the kit because it is specifically setup and tested for this application and is a superior unit to the Bell FMU. The Bell unit does has its place but in this case it does not belong.

Hilton

+1 - its not uncommon for a totally stock 5-speed S4 to put down almost 300 rwhp (and some well over 300 rwhp).

In addition to the WOT switch on the throttle assembly:

How old is the Mass AirFlow sensor? (aka. MAF)
Does the car have an O2 sensor, and is it working ok? (no cats does not mean no O2 sensor - e.g. could have an X-pipe with no cats).

You might also want to consider getting an Air Fuel Meter (AFM) that at least shows when running lean or rich.

Tim Murphy

Your assesment of some of the possible issues is spot on. The WOT switch (as Z said as well) is a likely culprit but I am not seeing any "accelleration enrichment" going on either which would point to the MAF. Still, he is low on power which might be a boost issue. If that is the case it might be good that he is currently a little low on boost and I can easliy fix that.

doug 88 s4

Thanks all,
I really aapreciate the help. Is the WOT something I can just look at to if it is functioning correctly

sidehatch

If it was dynoed on a mustang dynometer it can give you bs info., thats what happened to me.

doug 88 s4

No, it was a Dynojet WINPEP7

Bill Ball

You can check for the signal at the LH plug. Temporarily disconnect both the LH and EZK plugs from the brains. These are in the passenger footwell against the outside wall. The LH is the one closest to the outside wall. When you press the throttle, before you get to the floor, you should see continuity appearing across pins 3 and 17 on the LH plug. The image below shows the test procedure. If you do not see this result, try snugging up the throttle cable adjusters if you find slack. One adjuster is where the throttle cable passes through the firewall, while the other is on the throttle quadrant bolted on the side of the intake manifold. Just make sure not to overtighten them and lift the throttle plate off the stop.