Hello, I just had my new engine installed. a 383 all forged ai heads & cam and when the road test was done the engine builder was following the car and said there was alot of smoke coming from the exhaust which he said was oil. He said there might be a problem with the intake gaskets not sealing or the rings arent sealing. He also said the car was backfiring a little. So when i went to pickup the car and i started it up the fuel pressure was 77 @ idle. Is it possible the smoke is being caused by the insane amount of FP. I would imagine the backfiring as well is caused by the FP being so high. If it was oil does anyone have any suggestions about what might be causing it. There was no expense spared on this engine.

 

Fix the fuel pressure first, it will be way overfueled with that much pressure over stock without pcm programming for it. Was the car allowed to warm up a minute or two before the test drive, if not it would be seriously rich until closed loop took over.

An exhaust leak coupled with all that excess fuel will make it fire in the exhaust pipes. Get your fuel pressure back down to 43 or so and try it again. Maybe let the engine get up to temp and run for 200 seconds or so before driving it.

The only way I know to check intake seal is to pull the thing off, unless you can check with a vacuum gauge and seal off the pcv system and breathers to choke the air it would be getting from the crank case. You can look in it etc, but the only way to know for sure is pull it off. Before you put it back on i'd make sure the end rails werent hitting the block with no gaskets or silicone and that the intake was sitting tight against the heads at the top and bottom of the flange.

 

Who tuned it? Who selected the injectors and set up the fuel pressure? Did they do that intentionally? What fuel pressure regulator are you using? Any chance its an Aeromotive LT1 AFPR?

 

well i had pcm for less do the mail order tune & i dont think the fuel pressure was set up. yes it is a aeromotive AFPR. the injector size i chose from info from my engine builder. So i didnt get back until late last night so the first thing im going to do is set the FP. but im a little more concerned if there is oil through the exhaust.

 

I have just one question. How could leaking intake gaskets cause oil to get into the exhaust? I didn't think there was any oil pressure against the bottom or side of the head?

 

Seawolf there is airflow if there is a leak, there is a freaking monsoon that goes on inside of an engine wrt oil. It slings absolutely everywhere while in use.
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The easiest way to tell if there is oil in the exhaust is just to look in there. Or pull the plugs which are no doubt fowled now from all the excess fuel. Fix the problem and see if it still smokes is my suggestion. If it does do a leakdown test and if that passes, tear the intake back off of it and check out the fit and do whatever may need done and reinstall.

 

thanks for the replies. i will back home tomorrow and fix the FP first and see what happens. Im hoping that fixes the issue.

 

Massive overfueling will do damage to the ring seal fast and after that the fuel dilution of the oil will start to take out bearings.


A vacuum leak from an unsealed intake to the lifter valley could cause a lean backfire and oil burning if the fueling in the tuning/pressure/injectors were right.


The Aeromotive regulators were at one point arguably the worst you could buy fior the LT1, problems are supposedly fixed. Point being don't assume it is good just because it is new and supposed to be quality.

 

Yeah, I just pulled the dipstick and it doesnt smell of fuel but ill probaly change the oil tomorrow just as a precaution after i get the FP set. The engine has only been run for 10 minutes or so, So im hoping no damage has been done.

 

The Aeromotive AFPR for the LT1 has shown up as a problem in so many posts that I have been recommending against if for at least 5 years. They simply will lot hold up. (Note - I am not condemning ALL Aeromotive products. They make some excellent stuff).

Your injectors are flowing about 33% more than their rating, or about 80 #/HR. That is enough to damage the engine in fast order, as Dwayne has pointed out.

 

Thanks, I got the FP down to a normal range. With the vaccum line off i set it to 42-44. So with the vaccum line back on and the engine idleing the gauge inside shows 38-39lbs, but the car is not idleing properly so im assuming i have fouled plugs now. Thats the next thing im going to check

 

You're going to have a tough time getting the idle to work correctly with 60lb injectors. I am not sure how your tuneup is configured, but I will almost bet that it will always idle rich. The injector can only open and close so fast and that is the minimum amount of fuel it can supply when all it does is snap open and shut. Also when the stock pcm trims stuff it is based on milliseconds. 0.1 ms is ok with a stock setup that holds injectors open 5-6ms to idle but on a car that only needs the injectors at 2ms or less 0.1ms is a 5% change. Thats a swing of about 0.5-.7 a/f depending on where you're at for one step in idle fuel adjustment.

It has been done many times and worked out by a few but I have no idea what they did to make it run with that large of an injector and idle at any type of standard stable a/f at idle if they even worried about it.

 

ok, well i started to pull the plugs and i noticed that one of the plugs didnt have a wire on. it was hanging down around the cradle, plus it laid aganist the header and burned through the outer insulation, so im getting ready to crimp another wire to stick on, and see where that leaves me.

 

well i got the wires done and it still misses like crazy if you try to hold the rpms @ 2000 it misses bad, and the A/F gauge doesnt register anything. so i guess im going to pull the plugs tomorrow

 

Make sure all the plugs are tightened correctly and all the wires are on snug. If one was came off or was not put on others might be on wrong. I had one plug not tight and it sounded like an exhaust leak and ran like crap. Also, be sure all are on the right firing order.