Input on two topics below please!

1. Recently my engine has begun to sputter when accelerating, it's happens here and there when the engine is warm, but almost every time when i do a cold start. Only modifications
i have made so far is removing the screen on the air intake tube near the MAF. I heard it was a small air flow upgrade you could do, but now I'm starting to wonder if the AFR's are off because of it...

2. Once i resolve the above issue, I'd like to gut my catalytic converters to allow the engine to breathe better and deepen the exhaust a little. Will the factory ECU be able to adjust the AFR on it's own, or will I need a custom tune?

Different topic
3. I'm getting some condensation drips near the AC blower under the passenger side of dash. Could this be a clogged drain tube related to the AC system? Any tips on how to approach that would be helpful as well.

 

WE need to know what motor, year and any OBD codes to help you, with your old Chevy Caprice. Yes, you will need to clean the drain tube with a brush or wand. Don't use any air blowing device as that could cover your evaporator with material, making your A/C less effective. You do not want to tear apart the dash to get to the evaporator as it is difficult and time intesitive to do so.

 

Sorry about that.
1995 Caprice Wagon
LT1 5.7 liter with 180,000miles
my check engine light comes on about once a week for a day's worth of driving and then turns off again. I bought an OBD1 scanner to check, but it was a incorrect purchase and stated on the inside that it did not accept 1995 models with anything other than the 4.3 liter engine.

unfortunately that's all the information I've got for you so far.

 

It could be the IAC valve. I'd also suggest cleaning the MAF. You can do so without buying MAF cleaner, You can soak it in rubbing Alcohol for 12 hours, allow it to dry (you can speed this up with a hair drier) or use electrical contact spray.which works as well as MAF cleaner and comes in handy for other uses too. I would also clean your Throttle body out with some carburetor cleaner as well. 26 years
and 180,0000 is a very long time, so I think that your Chevy Caprice could use some TLC. Might check your fuel pressures too.

 

Yeah the wagon needs some love no doubt about it!
I've already completely gone through the suspension and steering using moog and belltech parts. Now onto the motor!
I will keep you posted with my findings. Thanks again!

 

So far, I have come across PCM performance as a solid candidate for my tuning desires with this old beast.
Does anyone have any other suggestions for other tuning companies?

 

Re the stumble, you can rule out the O2 sensors as
they're not used until warmed up. Cold stumbling
might be related to ECT sensor. I have seen flaky
ECT connections make for some really bad drivability
('99 5.3 truck) and intermittent problems like this.
ECT (at least on later LSx models) indexes the cold
enrichment and too much will make idle unstable.

Gutting cats will not affect closed loop operation.
The rear O2 sensors are there only to make the
EPA happy, throwing a light when cats become
inefficient. You'll see some codes after gutting.
Expect any performance tune would offer to
kill those codes, at least as an option.

Descreening the MAF seems like a good idea
but there are nuances. For one, if your air tract
has a bend within a few inches of the MAF throat,
airflow can be biased away from the uniformity
the MAF assumes in its calibration, messing up
air mass readings. Whether this pertains, not sure -
on later motors I'm more familiar with, the MAF is
ignored until engine hits operating temp and on
any throttle transitions.

The MAF screen will pop right out if you soak the
front piece in a dish of acetone overnight. Then
you have a screen that can pop back in. Lots of
folks take a more violent approach that ruins the
honeycomb. Yhe "Oreo" MAF used on LT1s and
4th gen LS1 cars can be disassembled and a
junkyard MAF screen can swap on. Beware the
impulse to "home port" your MAF, this will jack
the calibration.

 

Thanks this is super helpful. I have hear about to notoriously high gauge wire connection for the ECT sensor, and how it has been recommended to upgrade that proactively before the sensor fails and throws your car into a spiral of inaccurate engine codes, so i will definitely add that to my list. (if you know of any threads they could link this way that would provide more insight into this process, please do! )

after learning more about the breathability of the exhaust manifolds, etc, it seems the labor required for me to gut the cats seems to have very little if any ROI, so i will probably never do it.

I was one of those that took the more "violent" approach with the honeycomb screen after the MAF. I regret it to say the least. I am considering buying a new MAF for about $50 or just going to the pick n pull and grabbing one from there. not sure yet.

thanks again for the thorough response!