mmiller0

Hi guys,

I am having a little problem with my truck. When my truck sits overnight it hesitates when I give it gas. If I floor it, it bogs out and then after 5 seconds or so it it punches through and it works fine untill it cools down again.

A little background on the truck. It is the 4.3L vortec. I had a engine light code which indicated a O2 sensor (forget which one) but I cleared the code and it never came back.

Another thing is there is a rattle in the exhaust system. When I bang on the cat it rattles, so I bought a new one (still have yet to put it on).

Any ideas on whats boggin down by truck?

Thanks guys.

Mike

suzuki-guy

Your Catalytic convertor is plugged which would throw your o2 sensors off. There is a ceramic block on there that over time melts and forms a ball which clogs your exhaust system. I would replace it immediantly!

mmiller0

Ya thats what I was thinking. Thanks for the advice!!!

Mike

EvansBlue

You may have a PCV problem. Catalytic converter is a good thing to check.

mmiller0

Checked the PCV. I shook it and it rattled so I guess its not stuck. I just have to free up my stands to do the cat (got a Ford SHO that me and my pops are workin on).

Thanks for the help guys.

Mike

YooperJ

HI,
Did you get your problem resolved? My high speed is fine, usually a convertor will act up at high speed I think.

Well here is my problem. Back about 6 months or so I had a problem when I first started the car and moved forward it would hesitate badly until it cleared out and then ran fine. It was like when the float was leaking on a carb, after first start it would run bad until the fuel was all burned up from the fuel flooding the engine. I had no check engine lights and plugs were just changed 10K previous. I had to change the oil lines so I also put a new coolant temp sensor in and do a coolant change at the same time. Local parts store guy told me they sell lots of them and sounds like it could fix the problem. I didn't think so but since I need the coolant change, what the heck. The problem has continued but would clear up and run fine after the first minute.

The other day I changed the shocks and decided to do the CMFI upgrade. The plenum was really carboned up (115K) as was everything else in there. Cleaned it all out using carb cleaner and rags. Throttle body throttle plate was really bad also. Installed a new Standard brand Fuel injector and gaskets, all went fairly well.

Started it up and no fuel leaks but ran rough because of the carb cleaner. The initial problem is still kinda with me. Now, instead of just hesitating, the misfires a couple of times and then everything is just fine. Again, this happens ONLY on first startup of the engine and not again until it is shut off and restarted and then only sometimes. the engine seems to have a lot more pep now but this hesitating and missing is driving me nuts. No engine codes or service lights. No vacuum leaks that I can find, everything seems fine other than startup. Fuel Pump pressure with key on - engine off is 62 psi then drops to 58 psi when the pump shuts off. After about 45 mins it drops to about 50 psi.

Any ideas????:runaround: