Galler

Guys, My 1999 FRC has been struggling to accelerate.

Doesn't happen all the time, but its happening quite frequently.

It will start to accelerate, and then suddenly bog down, or it will be fine through first and bog down in second.


I am assuming the air fuel mix is off? whether is coming from a vacuum line or leak somewhere idk, suggestions are welcome at this point.

I have looked and cant find any? Maybe I am over looking something?

Two things i have noticed on hard accelerations when this happens, I get the smell of coolant? Which sounds/smells like a coolant leak obviously.

Occasionally I look smell burning oil after shutting it off.

3boystoys

What's the temp it's running when this happens?

c5vetteguy

Cats clogged? How many miles on your C5?

Galler

Under 200, much more noticeable if it hasnt been running very long.

Galler

just about to roll over to 70K

c5vetteguy

I replaced my cats around 65K with free-flow units. I immediately noticed a much smoother exhaust flow and better acceleration. Can't say that's your problem, but if there's a way to check them, it's worth a look. Good luck!

BigBirdLS1

Could be a MAF sensor too. Are you getting a check engine light? This might be a dumb question but are you leaving Active Handling/Traction Control on or turning it off.

If you can try to get a data logger and get some data while driving and replicate the issue. It should point you in the right direction.

Galler

I was curious about MAF sensor. However there is not a check engine light or any codes popping up.

I turn active handling/traction control off everytime I get in.

I have a friend who has a shop I'll check to see if he's got a data logger.

Fed Up

I thought I had a fuel or air issue on a hard downshift on the freeway, with subsequent power loss on the redline upshift; it turned out to be traction control kicking in, cutting fuel and power to about 50% on the upshift. I figured this out by removing my right foot and replanting it, which restored full power.

Try turning off traction before the downshift- This cured my issues on the freeway. May not fix your particular issue, but worth a try.

Galler

So update, yesterday I double and triple checked all the hoses and wires cleaned all the wires, the air filter and the MAF unit.

She was suddenly breathing again, no bogging down on any acceleration she was fast again.
My joys continued today to and from work,

Then I stopped and got gas, and all of the sudden it's struggling again?

Still no codes being thrown.

Any other ideas?

danasmith2816

Just curious, are these cars subject to fuel flow problems if the gas cap does not vent properly? Had that happen on a different vehicle and a new gas cap fixed the issue. Just throwing that out there, especially since your issue returned after you gassed up. Anyway, let us know what you find and good luck.
Dana

rhyno

check your intake manifold bolts...they loosen over 15 yrs. but a vacuum leak would be most 'bogging' at lower RPMs as air to fuel ratio is higher at lower RPMs.

cats would rattle if blocked.

Galler

Just replaced oil sender two weeks ago, all manifold bolts are properly torqued

Galler

Clueless on the fuel flow, gas cap issue. Maybe someone else can chime in

OneMoreVet

Any luck fixing this issue because I'm having similar problems. Cleaned the MAF sensor, cleaned the TB, checked and replaced questionable vacuum lines, sprayed cleaner around intake gaskets ... ect. (I've been doing lots of searches trying to figure this out.) Currently have P0175H although the car had P0171 & P0174 before I reset codes. Idles a little rough like it has a cam (could be normal) but I'm sure it doesn't.

The car just falls flat when I get on it. Not all the time but it's getting worse. The motor sounds sick when this happens, like it's not running on all cylinders. Any suggestions? And sorry for hijacking your thread!

MyNameIsJared

Not sure if it would affect your acceleration, but if you replaced the oil sender recently you might have left the vacuum hose behind the intake loose. I feel like I saw a few members mentioning something of the sort in some other threads. Maybe some more informed members will chime in.

Do you hear any kind of hissing coming from that area?

Galler

Update!

I did initially have the hissing sound and it was the small vacuum line. Figured that out the night I replaced it though without ever driving until it was hooked up. However this problem continued

I know a guy that owns a shop so I took it there and we hooked up a scanner. Turns out the scanner showed I was throwing 3 codes (DTC was not) all codes were for issues with the o2 sensors #1 and #2 up front and #2 in back.

He thinks that because these aren't functioning properly that it is basically flooding the engine. Causing it to basically big down and sound very throaty and heavy on acceleration. I will be replacing these next weekend probably.

If you know anyone with a shop I suggest having them hook it up. If not I will let you know in the next week.

Galler

Another update,

I have installed new upstream o2 sensors on the car and it seems to be running better (although it still doesn't feel 100%)

I am throwing codes
P0151
P0157
Which are both bank 2 and sensors one and two. Low voltage. If anyone has come across this and has ideas on places to check that would be great.

I am assuming that has something to do with how the car is running.

It has much more get up then a week ago, like I said though still doesn't feel "right"

Anyway, I'll be installing downstream o2 sensors this weekend. Maybe that will help? Doubtful but we will see.



One last thing, I gave it WOT on the way to work this morning around a corner. And the car started to jump all over the place. (As if it was dying and you get that bouncing feeling) any ideas? The engine was still under normal operating temps. I'm assuming it's directly related to my fuel air mix problem? (Assuming that's where my problem lies)

Corvette_Ed

I'm just tossing this out there, but when was the last time you replaced your fuel filter?

Black 02

I was thinking the same. On mine the regulator was built into it and a bad one could cause some of the symptoms you are seeing. If it's been replaced, check fuel pressure at the rail as your pump could be on its way out. Other than that, basic items like plugs, wires, filters, etc should all be current. It could even be related to a maf issue if its just falling on its face. Check the simple stuff first.