84wuzmy1st

I took it out tonight for some extended data logging, if I want to see if someone can take a look at my logs I attached to see if it shows anything notable?

The car just doesn't want to go over 2K RPM. The engine surges like it wants to go but it just can't. It's not like it starts to bog or stumble miss or hesitate, it sounds like a freight train being held back. Once I get off it and let the tranny decide to finally upshift, RPM's drop and I get to gain more speed, basically my redline right now is 2K and it takes a while and manipulation of the throttle the get the tranny to decide to upshift and let me gain more speed. If I stay in the gas I just sit there being all loud until I decide to get off it.

I think I am either going to remove the O2 sensor this weekend and see if it is a back pressure issue or take it to a local muffler shop and let them test it.

I had my wife sit in the car and give it gas while I felt exhaust coming out of the tailpipe, flow increase as she got it to 2K but not by a lot... probably no such thing as a hand test anyway. Banging on the cat lightly with a hammer revealed no rattle... dunno.

Question,

When putting a finger on the injectors, some are more powerful than others, and my number 3 injector is pulsing crazy strong or all the others are pulsing very weak.

Does this mean anything?

Fuel pressure at the rail at start up is fine, sitting around 37.

Not sure about the injectors, just putting a finger on them, they are pulsing, the #3 injector is hitting really hard, the rest are weak in comparison.

Just installed a new fuel pump 2 weeks ago, as the previous owner had mentioned after the car had been sitting for 5-6 years without being driven the sock could probably use replacing, which it did, it looked pretty cruddy. I cleaned out the tank by hand and just went ahead and replaced the pump and sock. The PO had replaced the fuel filter, fluids, plugs, and wires in an attempt to solve the problem but it didn't. I also put in a new Air Filter. TPS readings at idle and WOT look correct as well. Idle is too high, I need to adjust that so it will stop lurching when I put the car into drive, but I doubt that has anything to do with the 2K ceiling issue.

Any thoughts or suggestions would be greatly appreciated as well as anyone that could read my logs. Let me know if I should post them in a different forum.

84wuzmy1st

Ok, so I got a little more aggressive with the throttle tonight.

Under load when driving it is not possible to get over 2K RPM.

Revving in park it can get into the 3-4K range and feels smoother. Can something going on in the transmission be the issue?

Is back pressure under load more of an issue than when in park?

Is driving around with the fuel pressure gauge my next step to check pressure under load and not just at idle and revving in park?

cuisinartvette

ck it under load
how old are the cats?

Ransford2987

SES light? Any codes? How's the timing? Any ECM or memcal replacement/upgrade?

Ransford2987

Here's another thread worth reading. I don't know if it describes your issue, but it may help https://www.thirdgen.org/forums/dfi-...home-mode.html

luckydog0_18

My camaro did the same thing, it was the catalytic converter.I punched it out and put it back on everything was good as new,.

vetteoz

iTrader: (13)

Same symptoms on my '87 , would flat line at 3K but free rev with no load higher

armos

I haven't looked at the log, but I would proceed with checking fuel pressure, and testing with the O2 sensor removed. One of those is likely to reveal the issue.

I once read about some way to see signs of an exhaust backpressure problem in datalogs, but I don't remember how that works.

TPI-Formula350-

ohm the injectors

TTOP350

iTrader: (8)

Sounds like the cats to me.

84wuzmy1st

Wow, Thanks for all the responses. Sorry it took so long to get back.

I Checked the first few easy injectors to reach and they are coming in at 12 Ohms steady, only one will bounce down to 11 intermittently, the #1 injector. I don't see how to easily check the #2 injector with the plenum still on. I would think that 1 injector is going to need to be replaced but I would think that isn't causing the issue I am dealing with.

I am taking it to a local speed shop in a couple weeks and they are going to send a scope down the 02 sensor hole and take a visual inspection of the cat. I also have this feeling it's a clogged exhaust. They felt that would be easier than droping the exhaust considering the rust and age of the bolts, why risk snapping some of those if we don't need to.

Temp reading of the cat when coming back from a drive when warm show the same temps at the inlet and outlet, most likely the cat is bad.

fireturd350

iTrader: (8)

That's the same thing that happened to me when my dual CATs plugged up. I could only drive around 20-30 MPH at 3000 RPM. I tapped on them with a ball peen hammer and could hear stuff rattling around in there. After a few good smacks it would run decent for a couple miles then would clog up again. That was a long night to drive 20 miles or so home.

I did put some of that NOS Brand Octane Boost in at one point and could run 55+ MPH with it in the tank.

84wuzmy1st

Well I can get up to hwy speeds it just takes forever to get there since the car under load won't go past 2K, it runs fine under that RPM, silky smooth even.