Just had a shop replace injectors and fuel pressure regulator. Before taking it in had 80 lbs fuel pressure and paid the them for a diagnosis. 50 miles codes came back. Scanned it again fuel trims running negatives up to -12 at idle to 2k rpm. All sensors appear to operating in range. Engine runs good, haven't checked fuel pressure. They want me to drive it 200 miles see if the codes come back. Would a small vacuum leak cause this problem?
03 astro van 4.3 running rich P0172-175
- Thread starter Fitter30
- Start date
Did you change the oil.....Gasoline laden oil will cause negative fuel trims as fuel vapor will be sucked up through the PCV.
After running overly rich, The spark plugs won't just magically clean themselves.....There are situations where new plugs are needed.
After running overly rich, The spark plugs won't just magically clean themselves.....There are situations where new plugs are needed.
Weren't these the ones known for the fuel spider leaking fuel into the oil? You said the injectors were replaced, was it the whole assembly or just injectors?
Depending on the year the 4.3 had bad spider injectors. I had that on my 1998 C1500 4.3. The new body style truck went to 6 individual injectors which were way better.
If I remember correctly, they sold a retrofit for the 6 injector version as a replacement that was much better.
6 individual injectors don't know if it was a new harness but would think it would be. Van drove good before it took 200 miles to to set a check engine. Never saw black smoke or decrease decrease in gas mileage.
If your previous poppet injectors failed and were dumping fuel through the exhaust, I can almost guarantee that your primary oxygen sensors are shot. You say your fuel trims are sitting at -12% from idle to 2k RPM. Which fuel trims? To better understand what's going on, you'd need to provide both short and long term fuel trims, for both banks, at both idle and 2k RPM's. That information will go a long way in your diagnosis.
Idle 620 rpm. Rpm2219
Ect198*
Stft b1 -0.0% 3.1%
Ltft b1 -12.5% -15.6%
Stft b2 -0.0% -15.6%
Ltft b2 -12.5% -17.2%
Mfa .69 lb/ min. 2.29 lb/ min
Map 10". 8"
o2s b1 s2 .215v. . 225v
O2s b2 s1. .775v .875v
O2 voltage is constantly changing
Ect198*
Stft b1 -0.0% 3.1%
Ltft b1 -12.5% -15.6%
Stft b2 -0.0% -15.6%
Ltft b2 -12.5% -17.2%
Mfa .69 lb/ min. 2.29 lb/ min
Map 10". 8"
o2s b1 s2 .215v. . 225v
O2s b2 s1. .775v .875v
O2 voltage is constantly changing
