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95 LT1 car chokes only at WOT no codes

4130 Views 20 Replies 5 Participants Last post by  95 Firehawk
I have a issue that just started on my 95 LT1 Camaro. This car is my daily driver 200k miles on it, but I also have a 01 LS1 as backup :thumbsup:.
looking for some troubleshooting tips as I do not want to throw money at this issue.

Car runs great under regular conditions, starts right up. the only problem is when I mash the pedal "WOT" it chokes. Can someone recomend what I should check?
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have you checked your fuel pressure?

as per shoebox's site...
Normal pressure when the engine is not running and lines have been pressurized is 41-47 psi

To fully determine that you don't have a pressure drop off during actual WOT situations, you should tape the gauge to your windshield and take it for a test run. This will tell you if the pump can meet actual fuel flow demands at pressure and not just at a "simulated" WOT condition

for more info heres the link..

4th Gen LT1 F-body Tech Articles

good luck and post up your finding.
I replaced the fuel pump, Filter and FPR recently.

I disconected the MAF and took it for a ride mashed the pedal and it did not choke so I think that should eliminate the fuel pump correct?

I do have a fuel pressure gauge so I will start there just to be sure. I will post result.
then your maf is either dirty or going out already. Take it off and clean it with maf cleaner from any auto parts store. and if it doesn't fix it then the maf is the culprit.
ok so I took it out on the hyway with the fuel guage on it and it held presure at 41 even when it choked. any other items I should test?

I know it is not the MAF cause I had the MAF from the LS1... i replaced for a SLP one and swapped it in the Lt1 with no change.
did you clean the maf? and your sure the maf isn't going out? test someone elses maf on your car..

also did you make any changes to the car when the car started to choke? added mods? etc...?
swaped the MAF with a known working one and no changes.
no upgrades added engine is all stock except for the intake which was done at 100k. the A.I.R. pump did just die on it so I have it disconnected. I do not see that causing a issue since it does with the engine hot or cold.
I did replace the coil and ICM because of a no start condition I had but I cant see them causing this issue right?
when it's the ICM, the car will give you problems running. but since this is only at WOT then it's not the ICM.

since you say the MAF is working we will rule that out.

have you checked your spark plugs/wires that they are in all the way?
(i mention this cause my 99 ls1 spark plug didn't screw in all the way and i hooked up the spark plug wire and it drove fine and turned on fine, but at WOT it would choke/stutter)

have you checked for spark at the opti?

have you checked for vacuum leaks?
Plugs and wires were done 11k miles ago and they look all look fine I will check for arcing tonight.

Definatley no vacume leaks that was one of the first things I checked. all connections are fine and all the lines are in good shape.

Not sure what you mean by checking spark at opti. Wouldn't the car not run with out spark at the opti?
the opti can function under normal driving conditions or it can not work at all...

so check for spark at the opti to make sure it's working properly..

4th Gen LT1 F-body Tech Articles
ok so I checked for wires arcing last night and there was no problem there. Also I followed all the steps on SHBOX website to test the OPTI and no problems were found. I am stumped. Any chance a clogged cat would cause this? If I recall I have changed my cat 3 times in 3 years cause it would clog up so bad the car had no power at all.
1 last thing i can think of is cleaning the fuel injectors... clean all of them and try it after. thats all i got.

hm.... idk what else it could be... hopefully someone else will chime in with better knowledge/experience then me.

their must be something that was overlooked or it might be one of those fixes that have nothing to do with the problem and will solve it. (I HATE THOSE!!) lol

We'll gl and keep us updated.
I am having the same problem at first I thought it was only at WOT but it started acting up while cruising. Now it does not always happen during WOT sometimes it is fine in all gears. My only suggestion is to check the fuel injectors. I know that when i pour in some fuel system cleaner it runs better. I dont know what else to tell you since you have ruled out everything else. If i were you and had to change the catalytic converter 3 times I would just leave it off. Are you in a state that has emission testing?
Hey smokey,

I can rule out injectors they are all new.... they were replaced when I blew my head gaskets last year and had the heads rebuilt.

I was poking around today and took a closer look at all my vaccume lines. I pulled off the large hose that goes from the passenger side valve cover (breather hole) to the throttle body and lone and behold that sucker was cloged up like a artery on a heart attack victim. the hose and the entrance to the throttle body was clogged up with that white guey stuff that happens when the oil and antifreeze mix. I am hopping that when I clean that out and pull the Throttle body off and give it a bath in engine cleaner, that will solve my issue.

Its snowing now so hopefully by tommorow I can get it done and test it out. I will post the results.
BTW; I am in NJ and they test Emissions so the cat has to stay.
Ok maybe I should check my vacuam lines too. I have a mysterious vacuam line on the drivers side thats not connected to anything. Good to know you solved your problem.
Take a picture of the line you are talking about and post it. I can tell you what to hook it up to. A disconected line is not a good thing.
You need to put your 95 on an obd1 scanner, that not only does codes but does real time sensor data. Scan for codes first, as not all codes light the cel. Then do a running sensor scan to see if anything is amiss. If you don't know what the sensor readings mean, pm me with your e-mail address and I'll send you the pdf file, "sensor readings and what they mean".

If you don't have an obd1 scanner, may I suggest the Actron CP9145. It's available on ebay and amazon for around $140. It will scan your 95 and most any obd2 car also. For anyone with a 93 or 94, that has 12 pin dlc, you will need CP9127 adapter to scan your cars.

When your checking things, like the maf, remember that wiring and connectors can cause problems also. I would check the pcm grounds, engine grounds, pcm connectors & pins. Also since some sensors are interconnected for ground, one a completely different sensor having a problem can affect another sensor.

I suggest looking in this section for the GM service manual thread. Then download the 94 manual. It shares about 98% of info with your 95. Also have a 2000 manual there that will serve your 2001.

Manual will have a whole volume dedicated to driveability, emissions, and electrical. It has a pcm connector symptom chart, that is very good for helping diagnose problems, complete wiring diagrams, troubleshooting charts, component location views, etc.

If a hand held scanner is not your thing, then turn your laptop into a powerful scan tool. You will need a cable to connect car's dlc to usb port of laptop. $60 + shipping at
Then you will need a scan program. DataMaster is excellent. It not only scans but also logs data to a file that can be viewed in real time with the program. It comes as a free trial with 20 free scans and unlimited data playback. Get at Another decent scan program is Freescan. Again pm me with e-mail address and I'll send it to you. It's free for all times. Doesn't play back data logs like DataMaster, however.
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Couple cans of cleaner and good as new problem solved.

Anyone have any ideas how this happened? The only thing I can think of is that it got sucked up through the breather hole in the valve cover when I had blown my head gasket a few months ago.

I have the heater hoses bypassed so there is no water/antifreeze running through my Throttle body.

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