Still hesitating & loss of power/torque
 

right ive got a 1994 wrx & seem to be still suffering from a hesitation on mid to high boost & also there seems to feel a lack of torque/power, my mods are full decat,z4 ecu,walbro fuel pump,cosworth panel filter,hks ssqv, things ive replaced with new are coilpacks, tried two sets of spark plugs 6bs & 7bs both gapped to 0.65mm,bosch universal lambda also ive cleaned the boost solenoid & all hoses whilst checking for leaks along the way,cleaned maf & replaced the actuator with a second hand one, the car is throwing no codes up what so ever,i did think i had got to the bottom of it when i noticed a hole on the up pipe near the weld but a friend who works in a garage checked it out & said its the just a hole in the skin its fine, any help much appreciated cause im lost for ideas now:wonder:

First thing which springs to mnd is any/all of the coilpacks are breaking down?

Or perhaps you've got a dodgy batch of well stale fuel in your tank from last fill.

First though it might be a good idea to reset ECU and see if you're good again. If no luck, it might be a (cheap) idea to get hold of the OEM black plastic 'straight' re-circ DV, reset ECU again and see what happens...

Also to 'rule them out', it's worth testing the voltages of Lambda and MAF. Do a search and lots of threads should come up telling you how...

the coil packs where brand new unless i have a faulty one might be worth getting a spare & swaping it around, ive tried various fuels vpower/tesco 99 & reseting the ecu with no difference, i do still have the standard re-circ i think ive tried this but will give that another go, i did have it on the rollars a few weeks back not running the z4 though i had another ecu fitted with a polar chip(purchased second hand) but the outcome wasnt very good 240bhp 220lbs torque so i put that down to a faulty ecu or chip as it was only peaking at 1 bar dropping to 0.9 & running very rich top end so ive gone back to the z4 now until i have the funds for a esl chip but obviously i want to get to the bottom of this before doing anything else

Mine does that on occasion if I have been half throttle for a while then flooring it. It seems to always be arounf -0.5 bar.

ive just tried the standard re-circ & its still the same, id say mines similar mate probably about 0.6- 0.7bar just before it hits full boost it will hesitate jerk then pulls through it, my main concern is my loss of power & torque which was quite abit down on a standard wrx, i know i need to get it on the rollars again really with the z4 ecu fitted & see how everything is then fueling,boost etc but just trying to pick up any ideas along the way

Just a thought, there are people on here with a lot more knowledge than me but, is the Z4 fully mapped to your car specifically? My hesitation in the end was the daughter and chip someone in Japan had wired to the standard ecu. Once the Map was done on the Apexi all was fine.

My hesitation causes my boost controller to beep , if I let off and go back on the power it sorts itself out. I have a spare MAF if you want to borrow one but I still think your Lambda may be the problems. I burn through the universal ones like theres not tomorrow.

ideally yes i should have it all mapped to my car as the z4 is just the standard nonmappable ecu but they can usually adapt with light mods i have friends running good power with the same setups fueling etc is perfect but yes a taliored ecu is better which is what im saving for, thanks for the offer with the maf but ive just bought a maf to try which should hopefully come this week to eliminate that:thumb: joz8968 did point out some tests i can do with the lamdba so will give them a try, i thought the bosch universal lambda's where ok its just the ebay ones that dont last long

Didnt know that, Ill try one of those next. With the Lambda try unplugging and resetting the ecu, that might show you if its knackered.

if its the 3 wire version you have its model ls02 if i remember correctly you can get them from just lambda about £45 there alot better quality

:thumb:

See bottom of the link's page:-

Just Lambda, Subaru lambda sensors, Bosch and NTK zirconia and titania sensors by post

just curious what are the symptoms are a faulty map sensor? also i didnt mention in the aboves when it was on the rollars(fitted with the other chip) the power suddenly dropped about 6400rpm but held steady up the that which was abit strange as all plugs & coilpacks are brand new:wonder:

MAP sensor, as the acronym suggests, tells the ECU how much Absolute Pressure is present in the Manifold at any point. They are rated at a max absolute pressure level.

If it were to fail, then I believe it cannot tell the ECU to cut boost, if the turbo were to overboost (for whatever reason).

So if not monitoring boost level via a gauge for example, you could unwittingly kill your engine v. quickly!

thanks for the info that makes abit more sense now, boostwise im seeing roughly about 13psi which is about right for the z4

Yeah, that's 0.9bar - seems about right.

I know that the Z4 is certainly not over 1.0bar, so looks like you're okay...

Any ideas as to what else could loose me quite abit of torque then if I'm producing the correct boost? It Just doesn't seem to have much torque only produced 220ibs on the rollars but this was with the faulty Ecu/chip fitted but even now I've got the z4 fitted it doesn't seem no different? A friend has a 93 wrx his produced 257lbs his was running the standard ecu 240ps cat back & fmic it certainly seems to pull better than mine