Well mines a manual trans so it isnt the torque converter, not for me at least. And my throttle body was cleaned not too long ago and I just cleaned my IAC last week. It should really be replaced, but it works for now. My only guess is that maybe having the cats and smog pump removed causes the truck to run too rich with the egr connected. But I would think the o2 sensor would still make it lean back out. I'm wondering if the EGR itself is to blame for mine, and it just isnt opening and closing properly. I may just put the block off plate back on. I can't imagine a huge impact on mpg's with it connected anyways. I was just hoping for a little gain.

 

You'll prob start having detonation problems if you take the egr off. Egr actually brings combustion temps down and allows you to run more timing. Don't take it off. I have a feeling the problem you guys are having is in the ignition system. Any of you ever messed with the module in the distributor? Or the one on the side that your harness plugs to? I'm not sure what years your trucks are but I know the later 93/94 trucks stopped having the module on the side of the dizzy.

 

I have a 91 I6 4.9. I have not actually tried it but it does sound possible. I replaced everything emission wise without luck. I also noticed that it usually only does it when the engine is at running temps. Honestly; Im afraid that the solution is gonna be a ten dollor item after I already guessed away 100's.

 

my problem actually started right after i change the spark plugs and wires...so i thought the problem was cap n rotor went and got a new one...didnt solve it got a new ignition coil...didnt solve it...got 2 new sets of plugs and 3 sets of wires still did it...then went on the egr bidge on changed the egr valve,egr tube,evp sensor..still same problem...

i pulled my plugs out yesterday and there black..deff running rich..

02 sensor?...idk


(mines a 95 4.9l)

 

I would guess it's your plug gap then. Probably to wide. I'm not sure what it's sposed to be on those so take a look at your tag under the hood...it should tell you. That's where i'd start, the fact it did it after you did all your ign parts makes me think it's def an ign prob. Start with the gap, it's easy and doesn't cost anything unless you have to go buy a feeler guage. But those are worth having around.

 

i did all the gapping yesterday when i looked at the plugs...i do believe it suppose to be between .42-.46.....i regapped them some were alittle off but still the same problem..

 

My coil, icm, cap, rotor, plugs, and wires are all new. I recently replaced everything in order to do the timing bump. Currently I'm running an msd coil, new stock icm, 8mm plugs, brass rotor and cap, and platinum plugs gapped to .047. I have my timing advanced to 12.5 degrees btdc but I had it advanced all the way to 16 without this problem before. I want to switch back to copper plugs but these are brand new from when I got the truck back a few weeks ago.

I am also running a 180 degree thermostat. I'm thinking about going back to stock, which I believe is 190. I changed it because I was having overheating problems last year, turned out to be a clogged radiator. Could be I'm not reaching closed loop operation temps. But this is doubtful, as I reach just under the N on the temp normal gauge, and the idle drops down once the truck is warmed up. 180 should still be enough to reach normal operating temp

 

It is possible your platinum plugs are your culprit...the plats don't dissipate heat as good as the coppers. Personally I have used the plats with a 60k coil at a .055 gap and never had a prob. BUT that doesn't mean it will be the same with someone else.

You guys got one hell of a hard prob to fig out without throwing parts at'em. Neither of you have any check engine lights or stored codes in the ECM do you?

 

Oh an as far as your t stat I'd go with the stock 195. I had a 180 in mine as well and I was glad I went up with it. Heater works better an I it's runnin where it should be on the temp guage.

 

I don't have any codes pertaining to this. Before I replaced the egr components, I had a egr solenoid code because there was no solenoid. Now that code is gone. The only codes I have are for the smog pump because I'm not running it, and don't have its solenoids plugged in. Those 2 codes don't throw the light on though. I also have an ac compressor clutch code but that's unrelated as well.