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Engine Hesitation

 
Old 03-12-2019, 06:21 PM
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mannymendez25
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Default Engine Hesitation

I just bought an 84 Corvette as a project car. Car is a bit rough but has potential. The first issue I want to address is the engine hesitation. The car turns on and idles great but once I accelerate, the car bogs down or turns off. I have to accelerate ever so slightly to get the car going. Driving it from where I bought it to my house was not fun. The would not go over 25MPH.

One thing to note, I turned on the car yesterday and it ran normal, super smooth and accelerated like it should. I turned on the car today and same hesitation. Very weird.

Any guidance on what I should check first would be greatly appreciated.
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Old 03-12-2019, 07:45 PM
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t5258
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any codes?? Also, will it bog in park, or only under a load? Need more info to assist with this...
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Old 03-12-2019, 08:28 PM
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ex-x-fire
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Need to check the fuel pressure. Those tbi engines will run on very low fuel pressure, just not very well. Spec is 10-13 psi.
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Old 03-13-2019, 08:25 AM
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mannymendez25
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I ordered an OBD scanner to check up on the Check Engine light. How do I test the fuel pressure?

It bogs down in partk if i accelerate quickly.

Last edited by mannymendez25; 03-13-2019 at 09:21 AM.
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Old 03-13-2019, 01:26 PM
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ex-x-fire
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Get a universal pressure tester, it should have a T adaptor in it. Hook it up at fuel filter hoses. Start the car and note the pressure. Those tbi systems don't hold pressure after shut down.
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Old 03-14-2019, 08:29 AM
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Have you checked base timing?
How about spark plugs & wires?
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Old 03-14-2019, 12:23 PM
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mannymendez25
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I havent checked anything yet. I plan to start working on it this upcoming weekend. I will definitely start off with the basics, oil, oil filter, air filter, spark plugs, etc, but was a bit confused as to why one day the car hesitates and the next day it runs fine. I took the car for a spin yesterday and it ran strong, no hesitations. The day before that, I turned it on and once I accelerated, whether in park or in drive, the car would turn off. It seems to be an intermittent issue. Once I check the OBD codes and basics, i will post an update with my findings.

Last edited by mannymendez25; 03-14-2019 at 12:24 PM.
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Old 03-14-2019, 12:47 PM
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Why would you buy a car you don't know how to fix? I mean I get that you're here asking for help but if you don't know how to test fuel pressure take the car to a mechanic.
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Old 03-14-2019, 01:32 PM
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mannymendez25
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There is a first for everything. If I don't ask and I don't learn I will never do things on my own and be at the mercy of a mechanic. I am a bit mechanically inclined. I have done all the basics, oil change, drive shaft u-joints, bearings, brakes, etc, etc. I am not a lazy person and want all the answers given to me, just some advice from people that have done it already. I did some research and did find how some crossfire owners check their fuel pressure so now i know, without having to spend hundreds of dollars at a mechanic.

Maybe someone had the same exact issue I am experiencing and can post here and say, oh, I had the same problem, check the _______ and replace the ______.

If everyone were a mechanical genius then why would there be forums on how to do things?
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Old 03-14-2019, 03:14 PM
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ctmccloskey
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So "WE" can help "YOU"!

Hang in there, we Corvette owners have a lot of valuable experiences and they can save you from making the same mistakes we made. Let people read your posts and without a doubt you will attract the fellow Crossfire owners with plenty of experience!

The fuel pressure is like "Step One" on your 1984 Corvette. Step two would be to buy a set of the Factory Service Manuals (FSM) because they have more information about your Corvette than anybody because they built it. Don't use anything but the Helm FSM working on your Corvette.

Buying a Fuel Pressure Gauge is critical, some places will let you borrow them. You will also want to have a decent multi-meter to help trouble shoot the systems on that Corvette. You sound like your skills are up to the task so with the FSM and some time you will get this problem resolved.

When I first read your post I thought about faulty Catalytic Converters as they will keep an engine from being able to rev past idle without breaking down. I had a car that would start, idle, but not rev at all, it turned out to be the catalytic, changed it and the car was ran like it was new.

I wish you the very best in your Corvette Experience!
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Old 03-16-2019, 10:21 AM
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OK, I got the check engine error codes

22 Throttle Position (TP) sensor circuit - signal voltage low
34 Manifold Absolute Pressure (MAP) sensor - circuit out of range voltage, low or Mass Air Flow (MAF) sensor circuit (gm/sec low)
45 Oxygen Sensor (02S), left side on 2 sensor system rich exhaust indicated

I guess i will tackle these three issues first before anything else.
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Old 03-16-2019, 11:47 AM
  #12  
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First of all, welcome to the forum Manny. You can find lots of great advice in here and most are very nice folks. When you find the answer, please post in here, maybe new 84 owners will have the same problem, There seems to be some hard core crossfire 84 owners in here that will know the answer. Nothing against crossfire owners or their vets. heck, I am a c4 hardcore guy but like them all. Best of luck and the first thing I would check thats free or low cost is the fuel filter and pressure. Hope its not crap in the tank pluging your fuel sock ( sort of filter). Its just a PIA to fix, lol. BTW. there are sveral c4 owners here in he Indy area [planning on a meet at the drag strip here one wensday evening. perhaps even sunday meeting, be great to have one at the US Nationals here, parked all in a group. you didnt post where your at..oh, some owners in this forum may live near you and be wiling to help. Dont forget the wave..many owners of the older cars always wave at each other.

Last edited by ghoastrider1; 03-16-2019 at 11:51 AM.
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Old 03-16-2019, 04:02 PM
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Hot Rod Roy
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Since you'll have the fuel filter out in order to check the fuel pressure, that's a great opportunity to install a new fuel filter. Good PM anyway!

One of the neat features of the '84 CFI is the ease of checking the fuel injectors! Remove the top of your air filter, and watch for a nice smooth cone of fuel spray. Point your ignition timing light at the spray to see the injectors pulse! Our TPI friends are jealous!
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