8.2 GSI miss fires thru intake

heavyhammer

Cadet
Joined
Jul 17, 2012
Messages
10
Okay, this site is amazing and I have already taken advantage of the free advice many times. I am now posting because I don't know my next move.
Problem: 8.2 GSI "201" series, charcoal BYCCE s/n with 185 hours. I have a major missfire or stumble right off idle. This happens in the drive way or on the lake.

What I've done thus far:
New Distributor, cap. wires, plugs. Ran compression test all good. Removed injectors and had cleaned and tested,all good. Replaced O rings between the upper and lower intake. New low pressure fuel pump. On the lake this LP pump is barely running 5 PSI and the HP is at 50 psi (both under a load). Had entire fuel system apart and cleaned inspected lines, anti-siphon, reservoir, float and the cooling parts as well.
Timing is set at 10* BTDC, I have a simple scan tool to set into base mode. It shows no codes. I'm so tired of working on this thing. I know the shops in SLC are backed up and I haven't found anyone I trust yet. The boat is in great shape and with only 185 hours I can't believe that there is something "major" wrong.
 

Dave-R

Chief Petty Officer
Joined
Mar 18, 2008
Messages
441
Hey I'm close to you . I live in Nephi. I know about the shops being very busy this time of year. My boat was in one for 90 days, and they could not figure it out. I took it home and replaced the MAP sensor and she fired up. When you say it back fires thru the the intake, I'm thinking you may have the timing 180 deg out, or the wires wrong. I have had the same experience you are having, and here is what I did to correct it. First make absolutely sure the engine is timed to the # 1 cylinder TDC on the compression stroke. I used a small cork in the spark plug hole on #1, and when I crank the engine ever so slowly it will pop the cork out with a bang. Then I check to make sure the timing mark is aligned to the harmonic balancer at TDC . Now the engine is timed where you need it to be to set the distributor, to fire on the #1 cylinder. Your firing order is different than my 5.7. There is a procedure Fun times posted to set the rotor in the distributor to the correct spot. There is a small # 8 inside the distributor plate you align the rotor cap to. I will see If I can find this procedure. Very easy once you see the pictures. On my 5.7 GSI you don't even use a timing light. Good luck Dave-R
 

heavyhammer

Cadet
Joined
Jul 17, 2012
Messages
10
Thanks Dave. I know the wires are correct, I'll double check the #1 on compression at TDC. I'm surprised it would run at all if its off 180 deg. I was just looking thru my iboats history and I posted the same problem, with the same boat about 5 years ago. The joys of boat ownership.
 

alldodge

Moderator
Staff member
Joined
Mar 8, 2009
Messages
43,227
Having a misfire right off idle would lean me toward the TPS or a vacuum leak
 
Top