We had a similar sounding problem: rough hunting idle with codes P1130 (Lack of HO2S
-11 Switch, Fuel Trim at Limit) and, as I recall, P0170 (lean, Bank 1).
The real problem was the intake manifold gasket. Replaced it tonight and everything is fine. No codes, no rough idle, great power.
Along the way to this revelation, I say that because the problem is common on the 4.0L but I had not read a word about it on the 2.5L, we did the following:
1) Tested for vacuum leaks by spraying brake cleaner along hoses and fittings. As a result we replaced a number of older hoses including the PCV
hose, the PCV
and its grommet, and the injector O-rings.
2) Cleaned the MAF
specific cleaner, 2nd time anyway.
3) Replaced the IACV.
4) Tested the EGR
Valve and EVS (EGR
a) Repeated the test on the EGR
with it off the car. When we held a vacuum on it and blew through the opening the vacuum leaked down so this time we replaced the EGR
b) Cleaned the EVS. Ours appears to be the "enhanced" EVS, not the Duralast EVS58. It has a service port.
5) Cleaned the throttle body, etc.
6) Replaced the O2 sensor.
7) Replaced the fuel filter.
8) Tested the fuel pressure at the fuel rail. (Should be at or just over 60 psi. Ours was.)
As useful as the codes seem in theory, it is still a matter of finding the culprit. I have read of others with the same codes who needed a valve job, or a fuel pump, or just an oxygen sensor, or just a MAF
, or who just couldn't find the problem. We were patient and thorough. We were motivated to move along the diagnostic path selecting the cheapest possible solutions first. I really appreciate the support of the Forum and hope when others find solutions to their problems they, too, will post them.