Z22YH Bad idle, reduced power, stalling and hesitatation.

Hi,

I've just been given a Signum 2.2, engine z22yh, off my father. I was aware of the issues, I have access to a Bosch KTS diagnostics tool.

A brief bit of history of when the problems began, the car was having minor issues with power and the eml light was on, my father decided to take the car to a garage, who advised him the MAF was blown, and he didn't want to just put a new MAF on in fear that the same would happen with the new one.
then upon further "investigation" there was problems with the ecu and the car would need to be sent to a specialist to bridge tracks?

The car came back running fine, a few weeks later the real issues began, when the car is cold it seems to run okay once warmed up the irratic idle begins sometimes dying, the car really hesitates and has very little power, fuel consumption has dropped to about 17mpg, the garage then advised the car would need a new ecu.
I've cleared the codes and the ones that seem to keep coming back is p0110 and p0100, I monitored the voltage and air flow whilst increasing rpm 0.6v then steadily increases in relation to rpm, air flow is at about 12 and increases in relation.

O2 seniors report weird value bank 1 sensor 1 sits at 600mv then increases to 1600+Mv as increasing rpm bank 1 sensor 2 sticks for a while whilst cold at 431mv then it did increase to 600mv and then dropped to 79mv then 0 and stayed very low. I noted in the engine bay there is electrical tape across 2 wires in the harness so I'm not sure what the issue is. Also the fuel mixture shows rich flicking to lean briefly.

Any ideas I don't really wish to drive it like this
 
Personally run live tests with an Op Com or similar. I have a brand new un-used one going spare. Install disc, cable and OBD connector, you need a windows based laptop to use it.
Take the car for a drive and get it to normal temp.
Either have the passenger scroll through the measuring blocks and diagnostic options or you do it with someone else driving.

You'll soon see desired fuel pressure v actual

The lean/rich change is normal as mixture alters depending on throttle opening or closing plus the burn off of excess fuel/intake mixture.

What are the fault codes? should be a letter followed by some numbers then a dash then another number.

I'm still trying to get the bottom of why my 2.2 direct runs perfect 95% of the time then is gutless 3rd gear and above. No codes or MIL light at all?
On my next set of rest days I'm going to check the swirl flaps and if they're worn/sticking then they're being removed.
 
Last edited:
I shall get all the information today when I'm at work, are you sure it could be the MAF loom, just with it responding in time with the throttle, I have the TIS2000 for the car so that should help me with checking the wiring, also I noticed a considerable amount of fuel sat in the exhaust after running for 20 minutes.

The car is also struggling to start occasionally if it has been out for a run, it always starts in the end, just have to tap on the accelerator
 
Last edited:
Anyone? Car seems to get better then recently as cold is setting in the car seems to get worse, revs bounce and the throttle responds really poorly, until you get it over 2000rpm then go to idle, then the revs sit correctly as if the auto choke isn't working
 
Top