Rough at high speeds

[Jamest0809]

95 k1500 tbi, stumbles after I’m going 65+ newer plugs, new wires, new rotor,cap, module, egr, map, coolant sensor, new tbi unit, new fuel pump/filter

 

[RichLo]

o2 sensor?

 

[Jamest0809]

Haven’t replaced that, I don’t have a cat though, does that matter at all?

 

[RichLo]

Yes it most definitely does matter, that is the primary sensor for telling the computer how much fuel to give the engine once its warmed up in closed loop.

A lot of people upgrade to a heated o2 sensor rather than the factory TBI 1-wire to get it activated sooner. Lots of info out there on how to do this upgrade.

Edit, I'm talking about the upstream, pre-cat o2 sensor. The downstream, post cat sensor is just there to check if the cat is catting or not and it'll throw a permanent check engine light since you not running a cat.

 

[Jamest0809]

Yes it most definitely does matter, that is the primary sensor for telling the computer how much fuel to give the engine once its warmed up in closed loop.

A lot of people upgrade to a heated o2 sensor rather than the factory TBI 1-wire to get it activated sooner. Lots of info out there on how to do this upgrade.

Edit, I'm talking about the upstream, pre-cat o2 sensor. The downstream, post cat sensor is just there to check if the cat is catting or not and it'll throw a permanent check engine light since you not running a cat.

I only have one o2 sensor, and yea I have a code 32 for egr which I was reading could be because of no cat, I have a new egr and vacuum lines

 

[RichLo]

Oh yea, I forgot those had pancake pellet cats with no rear o2.

EGR and rear o2's are completely separate codes if you had a rear sensor. Definitely fix the EGR, that will cause drivability problems if its malfunctioning. I would also replace the o2, its a wear item that sends laggy signals way before it throws a code.

 

[Jamest0809]

Oh yea, I forgot those had pancake pellet cats with no rear o2.

EGR and rear o2's are completely separate codes if you had a rear sensor. Definitely fix the EGR, that will cause drivability problems if its malfunctioning. I would also replace the o2, its a wear item that sends laggy signals way before it throws a code.

Replaced the egr and o2, still does the same thing

 

[Jamest0809]

Replaced the egr and o2, still does the same thing

And it starts pretty much after overdrive

 

[RichLo]

Replaced the egr and o2, still does the same thing

Your computer could still have the Long Term Fuel Trim stored. Unhook the battery, leave it over night and try again.

 

[Schurkey]

1. What is the fuel pressure at higher speed?

2. Have you inspected the magnet on the distributor shaft? They often crack where the parts are riveted together.

3. Test the coil output power using a spark tester calibrated for HEI.

4. As always, connect a scan tool and verify all the sensors and computer outputs including electronic spark advance, and fuel trims.