Rough starts, idle, can't keep check valves

PERLCAT

MEMBER
1996 DODGE RAM
90,000 MILES

Have a Dodge Ram 1500, 90,000 miles. When I got it, the air conditioner would blow out the defrost on acceleration or under load, and it would hesitate on corners.

Put in a new vacuum check valve, new plugs and wires. Still ran poorly. Traced, found that the line to the cruise control was broken. (Vacuum gauge shows 24" vacuum) Replaced that, and found that the new check valve was now broken. Replaced that, and on the test drive, the check engine light was gone, and it ran good. Right up to the first intersection, where it started hesitating again.

When you accelerate, it pops and chugs, but once you get going, it is ok until you stop at another intersection.

I now have a second bad check valve. What can cause this? Bad MAP sensor? I kind of hate to just throw parts at it at random, but getting ready to.

1 Reply

HMAC300

MECHANIC
48,601 POSTS

Scan for codes and check fuel pressure first. Then clean throttle plate on both sides with choke cleaner and iac hole. Then check to see if purge solenoid valve is sending vacuum at idle on port to evap canister. It shouldn't. 24" sounds high for vacuum but it can be a screwy gauge too I have no idea about the vacuum check valve other than it was made in china as most of the stuff that comes there for auto s is crap and not worth thetime or money. Make sure it is installed correctly