I finally have my 84 corvette running. My problem now at intial startup. When cold, #2 and 4 cylynders tend to fuel foul at startup. I took the top cover off and found fuel pooled in front of the mouths of long runners for those 2 cylinders. Now the compression it pretty even across the board. This is a stock engine with a very close to stock cam specs and I mean instead of 115 lsa mine had 114, lift and duration are really close too. If I just go out in the morning, say with temp in the 40's and start it up and let it warm up it does an ok job of not missing too much and smoothing out in a minute or so. If, Like most ownders, I get in the car, start it up and put it in gear, then it starts missing pretty bad on those cylinders at the lower rpm when in gear. Exhaust temps are low because of not firing also.

I have had a few coolant temp sensors in the car but no changes with that. I tried different plug wires and spark plugs in those holes. It just seems too rich at startup but those are the only cylinders I get this problem. I dont' have the original injectors but aftermarket ones. I do have the pressure regulator close to 14lbs also, maybe too high? I know many reccommend that higher pressure anyway though. I want to sell this car but it is a drawback. Of course I can warm up the engine and after that it starts and runs pretty good. I was hoping to find someone that might have a set of stock injectors just to check and see if the aftermarket injectors have a higher flow rate. Also, new spark control, distributor. Heads have been redone so there is no oil leaking down through the valve guides and seats are fresh.

Thanks
Russ

 

I'd start by lowering the fuel pressure. Try 12, and see how that works.

It's not uncommon pull the lid and see fuel puddling in the intake. Is it only puddled by the mouths of those two runners? Is the IAC for that side TBI working?

 

I had a K5 that I just fixed that was running similarly. Crap cold and okay warm. One of the injectors ended up failing. It looked okay for a while and then eventually stopped firing all together...

The bottom left pin in your OBD connector is the fuel pump prime. Connect that to 12v + and check and see if the injector pod drips fuel with the pump running car off. If that looks good really try and examine the spray pattern on those injectors if you haven't already. I know you had another thread, I can not for the life of me remember the details though.

 

I had several postings on this injector thing. I kept noticing a nice spray pattern with my timing light but every once in a while I would see a ring of solid fuel in that cone. I saw it in both cones and with another set of injectors I bought from a different vender. I will check them again tomorrow because I haven't since I got the car running again. I am driving it the 35mph that is asked for when re-calibration the ECU and PROM. I am not sure what all parameters this "calibrating" affects but it does seem to be running pretty good when warm, a fairly smooth idle, no hunting like it used to. But not a stand a nickel on its edge smooth.

I think I noticed the pooling when I pulled the cover off in that one area before the 2 and 4 cylinders but will have to recheck again after I start it in the morning. I did port the intake runners where it meets the heads and I removed the egr runner over the top of the rear long runners, I think leading to 5 and 7? I am not sure if I need to somehow fill in the hole where the egr valve went. Not where it bolted on (I already covered it up) but where it now is open right above the rear runners, turbulence? I am sure crossfire guys know where I am talking about. Also I will check to if air is being pulled from the orifice above the IAC. Like most things on the engine, those are new along with the injectors but it seems you never know these days. I will also check the TPS to makes sure it is showing the correct voltage. And will try the fuel pressure too, bring it down to 12 psi.

Thanks, I will try to reply soon about the questions asked and if the fuel pressure made a difference.

Russ

 

I did take your advice and lower the pressure. It is now 10.5, a happy medium between 9 and 12 that is recommended. Nonw it starts up fin on these cold mornings. I never took the cover back off to see where it was pooling exactly. I just remembered that it did pool the last time I took off the intake cover. I thought I would try reducing the pressure first then check if that didn't help.

Now one thing that continues to show each cold start is a lifter that has to pump up. It is annoying and so many people tell me it is normal. These are new lifters. I bought another cam with lifters before this and had the same problem. The lifters all look the same. I got one kit from summit, one from rock auto and then I just bought a set of lifters from Crane. They all looked exactly the same on the outside, even the Crane lifter which were about 100 bucks while the other two in the kits, with cam were close to 125 bucks. I called summit to find out what brand they had and they didn't know where or what brand they were. My engine builder looked at them and said they looked fine. I took it to him because the first lifter/cam kit never broke in, wore out 4 lobes in about a week. My fault mostly because I didn't use break in oil that time. So now I have the second kit installed after having the engine block cleaned out. I broke it in the ususal way. I did pre oil the engine first with an old distributor I made for that. Ran fine, after break in I change the oil and filter and used a zinc additive with the new oil. I still get a clacking waiting for either one or two lifters to pump up.

I don't really want to pull the intake off again but my reason to do so would be to try to find that bad lifters, well leaky lifter or lifters. Is there a way to tell by pulling each lifter and looking at it? I did notice a few lifters having some play in them when I tried to do this very thing about a month ago. A few, 2 or 3 had some play when I pushed down on the top of the lifter with a pushrod. I considered replacing them with the crane lifters actually but when I got them and they looked axactly the same, I didn't. I know it was a good thing because I know they would have worn down the lobes again because of not being broken in together. So My idea was to replace the innards. They looked the same there too and I will bet the pieces on the insides are interchangeable. I didn't but that is something I am considering. but first I need to find the ones that have to pump up after each cold start. So that is what I am asking, is there a way to detect which are leaking down after a day of sitting?

Otherwise the car is running pretty good now.

Thanks
Russ