I just took my car out for its first test drive after the winter and the engine fix up..

I have changed some gaskets, valve seals, clutch, mx5projects IC, Tony dp and Tony cat. I still have the 1.8 injectors, stock pump, and standard vortec. Timing still aprox 8 deg.

Before the install, my car did idle at approx 14.7:1 and did 11.6:1-12.5:1 on WOT @ 5-5.5PSI.

Now it idles at approx 12:1 and does 13.5:1-14.5:1 at WOT @ 5-5.5 PSI

The WB have been moved from just below the stock sensor to a new almost back at the cat.

I also noticed a tiny leak from the conection where the two pieces of the DP conects.



Any thoughts?

 

Sell me your downpipe... Seriously though any leak before the WB sensor could be drawing in air screwing with your readings. Also if it's a gauge that requires a free air calibration. One of those wouldn't hurt after letting the car sit for a while. Furthermore, if those two things don't solve it than the the more power and quicker spool your getting from the DP could cause you to be over running your injectors. Time for an upgrade or redisc your FMU.

 

my guess is a vacuum leak.

 

Would it not be the opposite? With a vacum leak..

 

I'd suggest it may well be a vacuum leak, your engine might be drawing in extra unmetered air somewhere after the afm, the ecu doesn't know this and so will not add the extra fuel needed... therefore you may get lean readings, especially at WOT.
Or your LC-1 may need re-calibrating, easy enough to do.

Just so you know, I have changed my downpipe for a larger diameter model, I also have an exhaust leak on the slipjoint of the downpipe/midpipe, and my WBO2 sensor is waaay back in the catback section of my zorst.... and I have had no problems with leanness. hope this helps.

 

Under vacuum yes you would be pulling in un-metered air and running lean, however under boost you would be pissing OUT through the "leak" twice as much un-metered air and run stupid rich.

 

I have got a Zeitronix WB Datalogger, and it does not say anything in the manual about re-calibration. Does all WB sensors need calibration or only the LC-1?

 

it may only be the POS LC1. Although I have never had any problems, I personally helped fix two that have had nothing but.

 

yeah that's what I meant, last time I do any late night posting!

re-calibrate the LC1 and see how it goes.

 

I am trying to find out about if the Zeitronix ZT-2 is a WB that you can calibrate. If I cant figure this outm I will be back soon writing posts...

 

the Zeitronix auto re-calibrates

 

Thanx!

ThenI will have to find out if the small leak from the slip joint is a part of the problem.
Will also change my fuel filter (approx 2 years old), and se if it helps.

Ole

 

not fault of exhaust leak, fault of charge pipes leak.

i assume you're rocking the FMU, so if boost leaks, at idle the vacuum will be lower, therefore more fuel pressure, therefore rich. in boost, the fmu doesn't clamp down on the return line, therefore less fuel pressure, therefore lean.

 

Uppdate, The idle is not that bad as I first thougth. It idles at about 14.6-15.3.
I checked for vacuum leak today. I put some pressure on the system by a air compressor and blocked the end by the turbo. Found a very small leak at one of the coupler. The car acted the same after I fixed that.

However, I adjusted the WG one turn out (Now I have the WG rattle when I lift off the throttle :( ) and now the AF is about 13.3ish at WOT in 4th (I stopped pulling at aprox 5k rpm)

Is it possible that my stock fuel pump is just so bad that there are no pressure for the standard Vortec (12:1?) to build up pressure?

 

Is it possible that my stock fuel pump is just so bad that there are no pressure for the standard Vortec (12:1?) to build up pressure?

 

Ii it turns out that my pump is bad, and I buy a new 190hp. Will I have to calibrate my Vortec if I still want to run 5 psi?

 

You shouldn't need to do anything with stock injectors at 5psi with the 12:1 disk and the 190lph FP.

 

OK, but I am running tan top injectors (1.8).

 

Then you may need to adjust the disks based on the readings from your wideband.

 

Ok, then I will order a Walbro and see what happens to my AFR..