So I've had this car almost half a year and ever since I got it it's been running pretty rich (evidenced by strong petrol smell).
I've been trying to find the issue for a while now. Initially I thought it was related to the decat, but I learned that the decat would only affect the downstream sensor reading - giving a cat below efficiency threshold code and a check engine light, but on most cars, not affecting fuel trim (is this true for 1.8Ts)?
I've changed my MAF as the car was initially almost dying on cold starts and had to be revved to be kept alive - the new Bosch MAF solved this issue.
I've also changed the PCV system as the hoses above the oil filter housing were rotten and the petrol smell was getting into the cabin.
I can't find any leaks although I can hear hissing nearby the hose leading from the intercooler to throttle body, the clamp on the intercooler side had come loose so I retightened that today - hissing still present.
More to the point, I drove around today while watching my short term fuel trim and the numbers seem very weird:
-While cruising (foot off throttle), the trim stayed in the positive between 0 and 10%.
-It went negative when accelerating, then positive when easing off the gas.
So far these seem normal to me, here's what I found weird:
-When stopped at lights (foot on brake, car in netral), the fuel trim would jump above 10%, sometimes as high as 25%, and only coming down very slowly - jumping between say; ~7% and ~18%. Doesn't this mean the engine is dumping fuel as if under hard acceleration?
-When stopped on my driveway, (handbrake, car in neutral), the fuel trim would stay between -10% and 10%.
-When cold it was just flipping between -1.6% and 1.6%, but I could smell petrol intermittently.
Has anyone seen this pattern before? I'm pretty confused.
Sidenote: I haven't changed the N75 or the O2, the EVAP Purge Valve is fine and spark plugs have been changed for NGK ones recently.
Another question; I've heard that rich condition is sometimes caused by the thermostat (don't really understand this as of right now, but), on my OBDII as it was reading an Engine Coolant Temp of 98, the temperature gauge on the dash was sitting at 90. Is the gauge supposed to indicate the Coolant Temp or something else?
The reading rose with the gauge as it was warming up, but the gauge didn't show any values past 90.
If I missed out any information you need to get a better picture of the situation please let me know, thanks.
I've been trying to find the issue for a while now. Initially I thought it was related to the decat, but I learned that the decat would only affect the downstream sensor reading - giving a cat below efficiency threshold code and a check engine light, but on most cars, not affecting fuel trim (is this true for 1.8Ts)?
I've changed my MAF as the car was initially almost dying on cold starts and had to be revved to be kept alive - the new Bosch MAF solved this issue.
I've also changed the PCV system as the hoses above the oil filter housing were rotten and the petrol smell was getting into the cabin.
I can't find any leaks although I can hear hissing nearby the hose leading from the intercooler to throttle body, the clamp on the intercooler side had come loose so I retightened that today - hissing still present.
More to the point, I drove around today while watching my short term fuel trim and the numbers seem very weird:
-While cruising (foot off throttle), the trim stayed in the positive between 0 and 10%.
-It went negative when accelerating, then positive when easing off the gas.
So far these seem normal to me, here's what I found weird:
-When stopped at lights (foot on brake, car in netral), the fuel trim would jump above 10%, sometimes as high as 25%, and only coming down very slowly - jumping between say; ~7% and ~18%. Doesn't this mean the engine is dumping fuel as if under hard acceleration?
-When stopped on my driveway, (handbrake, car in neutral), the fuel trim would stay between -10% and 10%.
-When cold it was just flipping between -1.6% and 1.6%, but I could smell petrol intermittently.
Has anyone seen this pattern before? I'm pretty confused.
Sidenote: I haven't changed the N75 or the O2, the EVAP Purge Valve is fine and spark plugs have been changed for NGK ones recently.
Another question; I've heard that rich condition is sometimes caused by the thermostat (don't really understand this as of right now, but), on my OBDII as it was reading an Engine Coolant Temp of 98, the temperature gauge on the dash was sitting at 90. Is the gauge supposed to indicate the Coolant Temp or something else?
The reading rose with the gauge as it was warming up, but the gauge didn't show any values past 90.
If I missed out any information you need to get a better picture of the situation please let me know, thanks.
