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While my engine is getting richer I am getting poorer. It is my hope that I can get a quick reply to my dilemma of my new motor running rich. As my need for my daily driver, with my workload getting heavy and nights without public transportation is upon me.
To start I have a 1987 Corvette with the L98 engine and over 170,000 miles on the odometer. This past October I first encountered what I believed to be a non-operating Water Thermostat, which turned out to be a cracked L98 block between the #8 and 6 pistons. With out any used or rebuilt engines in the San Francisco Bay Area. I ran across an engine builder on CraigsList with a set of Bilstein Shocks for sale that happened to have just built a 350 motor for his 1982 Corvette. I bought this block from him which had pistons stamped with a 10 that my friend and mechanic told me meant this block was bored 10 over making it a 355 ci. The engine builder told me he had installed Flat Top Racing Pistons with 10.5:1 compression & new Crank with Hydraulic Flat Tappet Lifter’s. Along with the following Comp Cam; 12-239-3 - COMP Cams Xtreme 4x4 Camshafts with the following specs:
Cam Style Hydraulic flat tappet
Basic Operating RPM Range 1,300-5,600
Intake Duration at 050 inch Lift 218
Exhaust Duration at 050 inch Lift 226
Duration at 050 inch Lift 218-int./226 exh.
Advertised Intake Duration 262
Advertised Exhaust Duration 270
Advertised Duration 262-int./270 exh.
Intake Valve Lift with Factory Rocker Arm Ratio 0.462 in.
Exhaust Valve Lift with Factory Rocker Arm Ratio 0.480 in.
Valve Lift with Factory Rocker Arm Ratio 0.462 int./0.480 exh.
Lobe Separation (degrees) 111
Computer-Controlled Compatible No
Grind Number CS X4 262H-11
Using the L98 heads that were sent to a machine shop along with the Runner’s & Plenum to be cleaned and honed. The heads themselves had all new springs, valve’s, retainer’s etc and going from the factory 1.5 to 1.6 Stainless Roller Rocker’s. Yes, I see it states non Computer-Controlled Compatible. The engine builder said it would work and did, as you will see below.
Reusing the Injector’s and most all other parts from the L98 engine, although replacing all of the sensors and many other parts. The Fuel regulator is the original non-adjustable factory model. I have replaced the Spark Control Module.
I also had ordered a new Performance Chip which pictured would replace the factory Memcal in the ECM. It turned out to be one similar to what I had already installed on the L98 engine. What I had on the old L98 was a “Gorilla Chip” spliced into the wires of the IAT. This new (GForce Performance) Chip being the type that you splice into the wiring of the IAT also which is located underneath the Plenum. Let me backup here, when the engine builder & I first started the Corvette upon my picking it up upon completion & with the Gorilla Chip and factory memcal in the ECM it would not start. So I pulled the Gorilla Chip & factory Chip and installed my HyperTech ThermoMaster I had bought some 5 yrs ago. While at the time the HyperTech was too much for a stock L98 it did work with this new engine. Although it had some issues at idle at a stoplight and would go into a low enough idle to stop running, necessitating in a re-start.
Here is where my biggest problem(s) began. Me being the smart non-mechanic I am I at home attempted to install the GForce Chip, which I ordered and was to be programmed with all of the specs of this new engine. Installing it exactly as directed, it did not work. No amount of attempting to start the thing worked. What I did experience is a lot of “popping corn” sounds and 1 final “POP” from whence I do not know. My description of “popping corn” best describes what I heard when trying to start the thing. Like it wanted to start but would not. I checked the #1 plug, black and not at all like a non-rich running plug would look like. Buying a new set of plugs I replaced all. The #1 plug was the only one showing excessive richness. The other 7 plugs showed a small amount of richness but not at all like the #1 plug. It also appeared to have enough spark going to all of the plugs. Again, stock factory injector’s with 170,000 miles that were just cleaned only. (I bet you will tell me I should have changed the injectors to a new set but on a shoestring budget at this time I could not afford it. Now maybe I must afford a new set?)
I went back to the HyperTech Chip, which for over a week of driving gave me no problem. Now even with the HyperTech Chip it won’t start and slowly drains the battery in my attempts to do so. Before I continue to buy parts which I think will cure this problem and which is not curing the problem what should be done? Besides needing to install bigger Runner’s, Plenum and going to a BBK 52mmm Throttle Body, which I think I need more incoming cold air for this Cam and set-up. I am having my Factory Memcal reprogrammed for this new engine and the person doing this asked that I also buy an Adjustable Fuel Regulator. Is this a good recommendation?
I need help and I am not a “master engine builder” by any stretch of the imagination. Although I read this magazine with great interest, not so much understanding but interest. What I don’t understand is explained well enough for me to look up whatever it means that I am reading. Thank you,
To answer your question(s) I am considering an injector problem, none was there before the Chip Swap. My code Scanner shows only a 12, indicating all is normal. Yes, the original TPI & ECM are being used. When I try to start it I hear "popping" sounds from the headers like it is trying to ignite but not doing so. As I indicate below the new plugs installed show NO signs of Fuel or getting spark as they are as clean as when installed.
Here is what I am posting on my thread;
Yesterday I attempted to start the Corvette once again.
This past Friday I replaced a broken up Idle Air Control Valve Connector as pictured below. While this was a necessary evil the connector does not come with colored coded wires. Careful attention to connect the new wires into the same wires as on the old connector was done. I also replaced the Electronic Spark Control Module on the chance that this may have been bad. Since I previously checked the spark plugs and finding the #1 plug to be fouled richly, the other plugs were seen as slightly rich but mostly burning normally. So on this day I had replaced all 8 plugs with fresh ones. Many attempts at starting the engine gave me zero results other than good cranking but not catching fire. It also resulted in having to trickle charge the battery over night. This being the New Years weekend I refrained from further work on the Corvette to avoid the wrath of my wife.
This being Monday (yesterday) I again made my attempts to start the car. But first, I pulled the #3 wire, attached 1 of the good plugs I replaced and grounding it onto the header I saw that indeed spark was coming thru. Onto the even side of things I did the same thing with the #4 wire and spark again shown working. This puzzled me, good spark, having smelled fuel as if in my attempts to start the engine caused me to flood it in my attempts. So now I pull plugs #1-3-4 & 6, these being the easiest to get to. These plugs all looked just like they did when I pulled them out of the box to install. No signs of spark or fuel having touched them. This has become my problem now not being too rich as I first thought.
I called the gentleman who built this engine and who got me running in the first place to get his opinion. He suggested that I try to put some fuel, or not having that, spraying some WD40 into the Throttle Body to try to get some fuel into the thing to start it. I am apprehensive about doing this as it is not like my muscle cars of years past with a carb on top of the intake. I would not hesitate doing so on a carb'd engine having done so many times before. But this is a TPI Fuel Injected engine so my hesitation. Your thoughts on this?
At any rate I am now at a cross roads as to what to do. I am wondering if for some reason installing the GForce Chip after the HyperTech Chip had been running without issues was such a good idea. Is it possible that this chip swap caused some unforeseen problems? The HyperTech Chip is back in again with no better results in starting the engine up.
Or, thinking further, could the Fuel line, Filter or even the Fuel Pump be an issue now? In my email yesterday I mentioned "Popping Corn" sounds while attempting to start the engine. I had by way of cell phone the engine builder listen to the start up process and he says it sounds like it wants to start and I am hearing the spark firing but not enough fuel to ignite. That one BIG POP that I heard last week, is it possible it ignited in the runner/plenum area and knocked out 1 or more Fuel Injector from working properly? I of course can't tell and I did several times run my Code Scanner and every time it flashes a "12" as in normal. No codes to indicate what if any problems there might be.
I am waiting for a programmer to return my Factory Memcal Chip from the ECM with the reprogramming being done to my new engine specs. As I indicated in my earlier email, he suggested I go to an adjustable Fuel Regulator. Before making my car any richer and spending money I will wait to see what happens with the newly programmed Chip.
Last edited by Gregorio Lonewolf; 01-03-2012 at 01:00 PM.
I have taken this into consideration and spoke with the engine builder about this. He had set the initial timing, which ran fine until I did the Chip swap, at 12 degree TDC. It was just slightly rich but ran just fine. Having read some other threads I may be in need of taking the stock runner's, plenum and base manifold and trade them in for a different setup. Like a miniram setup possibly.