Well I've had the GURU MAP kit for a while and at first I could feel some hesitation but for some reason (maybe I got used to it) it went away. This car could get off the line well without hesitation/stumble and I could blip on the downshifts very easily.

But just a few days ago the problem of hesitation became very noticable. When just regular driving, coming off from a start it will stumble and when in neutral and I blip the throttle the revs dip below idle and them come back up instead of just revving up. And just as I thought, no more rev matching on downshifts because when I blip it the revs just drop and barely come back up. This happened maybe a couple days after I installed my test pipe and when it got really hot over here. Is it because of the hot weather??

Also another thing is that now sometimes when I start the car it almost dies, it gets very very close to dying but it'll catch itself. I searched and put in ACCEL Z=0 to +3% as well as all the other regular zones that show up when I let off the gas but still no help.

I put the car on the dyno this Thursday and at 16psi I got 245hp/285ft-lbs. But I have the 18psi chips so I'm going back on Monday and tuning it at 18psi. Is there anythign I should look for that might show on the Dyno that would pertain to the hesitation?

My mods:
GURU MAP Stage I (stealth) - 18psi Chips
Tial 38mm WG
Bursch 2.5" Testpipe - SFR 3" Exhaust
HKS SSQ BOV

I think those are all the relevant mods...maybe that will help

Thanks alot!

 

vacuum leak? thats my geuss, but I'm no expert.
~Eyal

 

Perhaps you should check the temperature sensor in the inlet pipe and, in particular, the leads to it. Make sure the leads haven't broken or fallen out of the connector. I had a problem where the car suddenly started running erratically. I found the temperature sensor leads had dangled down and gotten cut off by the blades of the alternator below the inlet pipe!

For the ACCEL MODE, my kit came programmed with TPS mode as the default. My recommendation is do not use TPS mode. For some reason, for which I don't have a good explanation, it produces the off-throttle hesitation that some people have complained about. When I switch to MAP mode, the hesitation is almost completely eliminated and it's much, much smoother.

If you have an A/F gauge, use it to program in the acceleration enrichment in the different ACCEL zones, using MAP mode. If there isn't enough enrichment, I find that the A/F goes too lean for a moment when the throttle is suddenly opened up and the car hesitates or stumbles. Add enrichment until it stops going lean and starts to go a little bit rich when you first hit the throttle. Don't overdo it because it will also bog down if it gets too rich. Without a gauge, you'll have to do it by "feel". The adjustment is quite sensitive, so add ACCEL enrichment in small increments (1%) at a time, starting from 0.

 

Danno at Eyal's house here!

Some times, oil clogging the clear plastic line coming from the intake manifold interferes with a good pressure reading. Might want to check that out and spray some carb-cleaner through that line. Other times, the vacuum T starts to leak and cause erroneous readings. Would be a good idea to put little zip-ties over the branches of the T.

I had another incident during the 1st day of the OTC. The monitoring the vacuum/boost on the controller showed that it wasn't responding anymore. I tried to adjust fuel in various ways, but it just got richer and richer in some places and leaner and leaner in others. Eventually, the manifold-pressure read-out got stuck on 98kpa, atmospheric pressure, no matter what I did.

Figured the manifold-pressure line popped off. So I took a look down there and the line had melted to the resistor packs for the cooling fans! So I snipped off about 2-feet of the vacuum line and replaced with some spare rubber vacuum hose. That took care of getting correct pressure readings to the MAP computer.

I've found that part of the problem with the off-idle stumble is due to the transition between the idle and partial-throttle maps. This occurs in reverse as well when you let off the throttle, like entering a turn. In which case, the DME cuts the fuel until you coast down to 1600rpm or so. Then if get back on the gas, it stumbles a bit.

The trick is to not use the idle maps at all. Here's the procedure I've found that makes low-end drivability a lot better:

1. unlock idle stop-screw locknut.
2. unscrew idle stop-screw by 1 full turn (makes throttle open more at stop)
3. lock idle stop-screw locknut
4. screw in idle-adjuster screw by 2-3 full turns (compensates for larger throttle opening)
5. verify that TPS does NOT click when throttle is closed and opened

That's it! Some of you others with MAP kits might want to try out this adjustment and see how it works for you. Also the 18psi MAP chips have removed a lot of this stumble as well, so email me to get an updated copy.

 

Good Morning,

In my humble opinion try this. First document all of your values. Find a good hill with a slight incline and put her in reverse using as little throttle input as possible. The cells that you want to play with are: 500, 505, 510 and 600, 605, and 610. Although neither the data recorder nor the hand held shows that the car uses these cells it appears that my car does. Try significantly backing off the values until A/F is approximately 13.9.

I use the TPS Accel; however, do this first. Go to Row Step then to MAP –10 MAP+10 and where you see TS (49v) 0% hold the both Edit buttons down. Here you can reset your throttle position (first close then wide open (WOT)). For WOT you have to fully depress your throttle.

Next spread out the TPS angle.

I am not clear why this works for me but it does. Good Luck

 

Thanks alot guys I'll try it out this afternoon.

Danno: Will doing the idle-stop thing remove the use of the idle maps? And what are the idle maps? Thanks!

 

Danno,
In the garage right now and just tried the idle screw-nut procedure but I think I'm doing it right. After doing that procedure what should my idle be at?

Thanks alot

 

bump...

 

Sorry to butt in but I'm sure Danno means screw IN throttle stop screw by 1 full turn ie clockwise. the comment in brackets is entirely correct and Im sure you picked this up.

Definitely not trying to be a smart ***

 

Haha that makes more sense now, I'll go try it again later today

 

Your idle should be the same as it was before you started.
You will open the throttle giving it more air that way.
Then you should compensate this by closing the air bleed screw so that your idle will be restored.

You could achive the same effect by adjusting the TPS.

Tomas

 

There are two adjustments here. One is to have the throttle-plate more open so there isn't such a sudden change in pressure when closing and opening the throttle. Closing down the idle-adjustment screw compensates for the extra air coming past the butterfly.

The second adjustment is to disable the TPS click and keeps the DME on the partial-throttle maps. There are three maps used in the Motronic system: idle, partial-throttle, full-load. The issue with transitioning between the idle and partial-throttle maps is that the idle map only goes up to about 1200rpm. This affects partial-throttle drivability when you're cruising at very little load but high-RPM, like coasting into a corner. If the throttle closes that last bit, it drops into the idle map, and if you're above 1600rpm, the DME cuts off the fuel. Then if you re-open the throttle, the DME starts up the fuel again. This can cause a surging pogo-stick type of bouncing. So by disabling the idle-map, you never get the fuel cut-off and things are much smoother.

 

I just got around to doing this last night. It definitely more smooth on the on/off throttle transition. The car lost its CHUG if the throttle is opened too quickly at low RPM. The hesitation is still present, but it isn't nearly as noticeable as the transition is a lot more smooth now.

I also noticed that starting the car is a bit harder as it doesn't want to idle for the first couple seconds, but then it's fine. After replacing my blown divertor valve with one I borrowed from AlexE my idle MAP dropped from 41kpa to around 35kpa, and then after fiddling with the above mentioned procedure I'm seeing idle MAP at around 32-33kpa. On decel overrun, with blown divertor I was at about 33kpa, after divertor replacement I was down to 26 and now I'm hitting 18kpa (that's actually in the 1xx zones).

Drivability is close to stock again with the exception of the ridiculous increase in torque all the way up the RPM range and the occasional need for a bit of throttle when I start it.

Thanks Danno!

Justin