i've got a LT1 in a 94 buick roadmaster. The problem is it spits and sputters under acceleration and it sometimes does it at idle where you can feel it through the car. I changed the spark plugs at that didnt help. I'm just wondering if you guys have any suggestions on what i should look at next. The car has a lil over 208,xxx on it.
Yes, it's fairly expensive too. Scan it first and see what you find before just hrowing parts at it. It may be something as simple as a dirty MAF, although, if it has all original parts and that many miles, it is due for a good general tuneup...opti cap and rotor, plugs, wires, 02 sensors, etc...al the normal wear items. Good luck, Bill.
Really, with that many miles on it you should get a good tech to look everything over. Could be any number of things from bad cap/rotor, EGR, MAF, 02's, IAC. Have a log pulled on it, that should tell you what's going on.
If it ends up not being something simple. i'll probly take it to a shop. The car really isn't worth doing any major repairs to though. The tranny is on a downhill slide now its shifting into 4th and reverse slow. So when it goes down ill probly just pull the engine and junk the car....
Well, just for s**ts and giggles, try running some TECHRON through it. Only cost you a few dollars for a bottle at auto parts store. They other to check is your spark plugs. Spray a little water on them, at night, and see if there is a light show under your hood. Those are some easy, inexpensive things to try.
I might have to try something like that. Whats the reasoning behind putting water on the plugs? It will spit and sputter if you floor it in park or neutral. When you do that it will keep doing that till you let off the pedal.
I did take it to auto zone to have it scanned but they cant pick up any codes unless the cel light is on.
There's a lot of things that can be acting up without turning on a CEL. If your plug wires are original, it's for sure they need replacement. If you mist water over the plug wires, while it's running, any "leaks" in the wires will be exposed by the water creating a ground of sorts. If you do it in a darkened garage, or at night, you'll see the little sparks flashing around the wires.
Does the car do it if you accelerate, slowly, up through the gears? Still sounds like ignition, plugs, wires, cap, rotor etc.
not necessarily. if you have enough pressure to run but not at wot
go to autozone and get a free rental fuel pressure gauge or you can throw parts at it
I think I would still try to find someone who can pull a datalog for you while you're driving. MAF, IAT, fouled 02's, could be ANY number of things. For instance, if your MAF has stopped working, or is working intermittently, your engine will revert to speed density mode to run your engine. With that many miles on the engine, your VE tables are surly out of whack. But like you said. unless it's something simple, which it still could be, it's not worth it to get it repaired.
ya i'm not counting it out yet. A buddy of mine has a tool to do the data log so we are gonna try that after i get off work. If not ill pull the motor for a future project or sell it to fund an ls motor.
I got a data log pulled on it and its sensing knocks so it retards the timing. it retards it as much as 21 degrees when is senses the knocks. I dont think the engine is actually knocking because you cant hear it. The only code it was throwing was a egr code.
Unbolt the knock sensor from the block, wrap it in a rag and tie wrap it up away from the engine and take for a ride, see if the problem goes away. Or you can just unplug it to test but it will set the CEL if you do.
Also a defective EGR valve can cause pinging if it is not opening. The knock sensor will hear pinging long before you can.
How were the fuel trims, were they close to the center in the data
Both the timing retard and the EGR problem could be causing your problem. Where is it sensing the knock and pulling the timing, idle, under accel, high RPM? To diag your knock, check to make sure something else isn't causing the knock. Loose exhaust, or something else hitting the block, oil pan, chassis near the block.
You can try to run some high octane fuel through it to see if it eliminates the problem. If there is a large buildup of carbon in your combustion chambers that could cause it also.
As for your EGR, clean the EGR system, replace the EGR. If your EGR is sticking or fluctuating, could cause your problem.
It senses the knocks right off idle and as far as i know nothing was hitting the motor or loose. It should have good fuel but i will put some premium in and see if that helps. I'll also try unplugging it too. i'm not sure where the fuel was at i wasnt running the tester.
i unplugged the knock sensors and it helped some but it still sputters some. i'm gonna replace one of the knock sensors thats coated in oil. i'm beginning to think its in the distributor.
Ryan, I'm really surprised that the distributor has lasted that many miles. The early ones were plagued with problems which was partially cured when GM revised the distributor by adding vents to keep moisture from accumulating within the distributor body. But, it seems they either work or don't work.
I had a very similar problem with a '94 LT1 in my wife's Camaro while still in warranty. After a lot of head scratching at the dealership because of no codes, it turned out to be a bad coil wire. The mechanic told me that the coil post (aluminum) had some corrosion, so he cleaned it and replaced the coil wire.
You may want to try a new coil wire before diving into a distributor job.
I later had to replace the distributor when it failed out of warranty. I was driving it and the engine just shutdown and would not restart. When I called my wife to send a tow truck, she thought I had blown the engine driving it hard and was not happy. LOL. Inspection revealed that the distributor just tore itself to pieces and had lots of moisture corrosion.
The early OBD1 LT1's had no misfire detection and some of the OBD2's particularly the '94's and some '95's had early OBD2 with no crankshaft position sensor which is necessary for misfire detection. It was '96's and up that all had the crankshaft position sensor and misfire detection in the program.
The point is that the newer would throw a misfire code and lead you straight to an ignition issue where as the older won't.
I have a '94 Corvette LT1 motor in my ride and have noticed it is very sensitive to low voltage which causes it to stumble and run rough. A check of the wiring, a new battery and a high-amp alternator seemed to have fixed the problem.
i put a new battery in it and it helped the problem. It still sputters some once it gets warmed up so i'm gonna change the plug wires and distributor because we have never had them changed and see what that does.
I "upgraded" to a Powermaster 47294 150-Amp Alternator. that solved my problem. A 105-Amp Delco 12-SI was inadequate for my LT-1 to run properly. It's $145 on Amazon Prime. I scored a used/like-new unit for $94. They sell a polished version for about $100 more, but "chrome won't get you home".
Could very well be a distributor issue from what it sounds like. Do your standart cap&rotor maintainence. That's something you would want to do anyways with high mileage.
If that doesn't work, you could always get yourself a good old fashioned carburetor on top of that intake to eliminate the possibility of a fuel system issue. Plus, you're on a hot rodder forum. You're the type of person who needs to get a good ol carburetor conversion. Once you ditch EFI, your life will be better on every level.
IDK how the TPS on this car affects the fuel delivery, but CHeck that out. Maybe your throttle position sensor isn't sending the right message to the ECU which = not sending the right messages to the injectors. ONce again though. TBI or whatever that chevy engine has might be different.
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