67Olds442x2

I have a 94 coupe with the LT1 that I just got a week ago. I'm new to this type of motor, I'm used to big block Olds motors where I can actually see and change parts.
The car hesitates and/or bogs down when I try to accelerate from a stop went the engine is cold. Seems to work fine after it's warmed up but will bog if I jump on it too much. The car has 100k miles on it and I don't think it was well taken care off. I assume it has to do with the fuel system or throttle plate maybe. The engine may need a complete tune up? I pulled the easiest spark plug I could get to and it looked fine. I have new ones to install but looks like a day job. I know nothing about fuel injection. Thanks.

TWISTERUP

Assuming you're not seeing any warning lights and the ASR (traction control) isn't active at times. Some folks say the ASR feels like a "bog" and I agree. I'd start by checking fuel pressure first. These aren't exact specs for yours but they'll get you there.

42-47 psi ign on -engine off
38-42 eng. running

Spark plugs,wires air and fuel filters are all maint. items which should be replaced along with all the fluids being changed assuming you don't have service history on the car. Another possibility could be dirty injectors--but I'd check pressure first.

383vett

The first thing I would do after buying a used car is do a tuneup; wires, plugs, cap, rotor, fuel filter, 02 sensors, check timing, oil, filters, etc. That usually will resolve any issues. If after all that, there are still issues, check fuel pressure and injectors.

67Olds442x2

No warning lights. It bogs to the point where the car won't move until I play with the throttle. The ASR, is that the unit that looks like it controls the throttle cable?

I do need to do a tune up and change the mentioned parts, need to get a service manual first.

Thanks for the replies.

C409

...... Don't waste money on a Chiltons or Haines ... buy the Helm factory service manual ... you can find them here occasionally or on the auction sites , or buy direct from Helm ........

67Olds442x2

I wasted some on Haynes already, basically useless, should have known when I paged through it. Factory service manual the only way to go. Got one for my pair of Olds 442's and had gotten one when I bought my new 1988 C-4 coupe years ago.

TWISTERUP

[QUOTE The ASR, is that the unit that looks like it controls the throttle cable?

Yes on the drivers side fender well,there should also be a button to the left of the instrument panel to turn the ASR off which would be the way to check if that's what you're feeling. With the ASR on and active there is also a light which should flash saying "ASR Active" in the message center.The ASR shouldn't kick in on a stock LT1 except with hard accel. from a standing start/wet roads or tires in poor condition IMO. Manual trannies would be easier to loose traction and turn the ASR active. From your description the "bog" sounds pretty severe--I'm guessing you likely have other problems.

As far as getting a FSM try ebay they come and go there. They are year specific and you'll get more info with the 2 volume version than in the single preliminary edition

TWISTERUP

There's some good info here on fuel injection IMO whether someone is new to fuel injection or not. It's well written and easy for a newbie to understand. I've had a copy for years so i'm guessing they're still in print. I imagine other places like Amazon/ebay sell them--this just happens to be where I bought mine.

http://www.bentleypublishers.com/che...eng-82-01.html

Repzard

With that many miles I would worry about the Optispark.
If you dont know what it is, You will soon enough.

Its the biggest problem with the LT1 motor.

To some it up its the distribiter unit for these motors and its in a real bad location,Under the water pump. Idiot engineers at GM on drugs to some it up.

67Olds442x2

[QUOTE=TWISTERUP;1578029471][QUOTE The ASR, is that the unit that looks like it controls the throttle cable?

Yes on the drivers side fender well,there should also be a button to the left of the instrument panel to turn the ASR off which would be the way to check if that's what you're feeling.


I'll have to turn it off and try it. Thanks.

Mohammed_z

+1

that's what I did ,

new plugs
new fuel filter
new fuel pump
cleaned injectors
changed engine oil
changed trans oil
changed map sensor " which was causing the same symptoms you have "

waiting list : new wires + optispark + o2 sensors

congrats on your new vette

67Olds442x2

Yeah I was wondering why the wires went to the lower front part of the engine. If I have to change that (Optispark), it looks like a few things will have to come off first. Is it something to change over time, like maybe a rotor and cap, or is there a sign that it's bad? It's not a lot of money so maybe I should change it along with wires and plugs just to be safe. I need garage space now, not a 30 minute job like I'm used to.

67Olds442x2

Well I'm making my list of parts to buy and when I get the service manual, time to get to work. I guess since it's actually my 17 year old son's car, he will help. After driving the car, I got the fever again and need to get a car for me, a C-4 for sure. Thanks for the replies. I'll let you know how it turns out.
I need to upgrade so I can post pics.

Mohammed_z

here is how to change the opti , step by step


http://forums.corvetteforum.com/c4-t...-pictures.html


you can do these replacements without the need of the service manual , just search through the forum and ask here.

67Olds442x2

Well I took the car out and turned off the ASR. Car didn't bog down, I assume the settings on the ASR are off or the unit under the hood is bad. Settings are probably built into the unit. The cover on the unit is loose, I'll take a look at it. When I lean over in the engine bay, the first thing I want to grab onto for support is the ASR unit. Thanks for the tips.

67Olds442x2

Turns out the ASR is not the cause. Need to look elsewhere. Tune-up time.

Jet Jockey & C5

Any update? I'm into the same issues with my son's 94 LT1. Starts & runs great under normal acceleration. Bogs significantly under hard acceleration. Just spent $5500 this summer on full tune up. Issues still there....

67Olds442x2

I changed plugs and wires so far. Still an issue. I haven't put much time into it in awhile. My next avenue would be the fuel system (fuel filter and injectors) and an Opti-spark cap and rotor. The car has 102K miles and wasn't babied I don't think.
$5500 is a lot to spend and still have the issue, you must have replaced everything or put aftermarket high performance stuff in.

anciano

My '94 tended to bog when accelerating uphill when the engine was hot. I pulled the EGR valve which was crudded almost solid, cleaned it out and the problem was gone. Can't say if that was the cause or not, maybe just coincidence. I also put in a manual fan switch to keep temps down, so that may have been a factor, too.

Anyway, it's good now. Best of luck.

powerpigz-51

The first part I would check is the fuel pump.