**UPDATE** On fuel pump, and Lean condition

[vetteboy86]

I purchased a new fuel pressure guage, and it works much better. For some reason I think that pintle on the schrader valve is off center, because the old guage just would not give me a good steady reading.

Right now the Fuel pressure is set at 46 with the vacuum line unplugged. I also put a heated O2 sensor on the car. Before the car was running lean all the time per the EASE software I am using. The O2 voltage hardly rose above 200 millivolts.

WIth the heated O2 sensor on the car, the car transistions from rich to lean normally now. The O2 sensor voltage now goes from 100 mV to 900 mV like it should. I also do not have any more spark knock, and the car pulls incredibly harder. I think I am safe for now, I notice it does pull some timing right when i get on it, but I can work that out.

Just wanted to let everyone know of the situation, and thanks for all the help.

 

[Vettefan87]

Um...If you dont have spak knock why are you pulling anywhere from 3-6 degrees KNOCK retard?? :confused

 

[Agent 86]

I forgot to mention that on my fuel pressure tester the center pin on connection is adjustable. Maybe yours was too and did not push the valve in the shraeder valve in far enough to get a steady reading.

 

[vetteboy86]

Yeah, that makes sense. I had to get a new guage, I just couldn't except the fact that my fuel pump was on its way out. The new guage is much better for accurate readings.

 

[MoeJr]

I don't think you can ever get 0 retard. When you punch it you will see a spike in the retard then level off. When I used to have my 87 GN we used to look for no more than 4 degrees retard. Sometimes top performance comes when the timing is retarded from optimum. If you are only getting 3-6 degrees retard then I wouldn't be too concerned especially if it hits six then pulls back to 3.

 

[tigmaned]

fell me in why you want 46psi fuel pressure, not a stock L98? from what i have been reading about my 86 39psi is max, so why i am asking.

 

[vetteboy86]

If you take a look at my mods, I am not running a stock L98. It is somewhat modified. So far it is trial and error, so when I get some more time I will actually adjust it and see what kind of improvement I get.

However my brother is running about 42 i think with bolt ons, and his car pulls very hard. Some say there is some HP to gain by increasing the fuel pressure a few lbs.

 

[Edmond]

With these mods:

383 Stroker(Eagle Rotating Assembly),cam, ported heads, ported plenum, Ported and siamesed runners, Big Mouth Manifold, Holley AFPR, accel coil, accel wires, accel injectors, Vortex Ram Air, Air Foil, MAT Relocation kit, TB Bypass, Dual Exhaust, 2400 RPM stall torque converter, Pioneer Head unit, Infinity speakers.

I would say he is far from stock.:L:L:L

Where did you get that Eagle rotating assembly from? Are they pretty good?

 

[LT4man]

FWIW,

I would do the following:

Install an OEM fuel pressure regulator with the vacuum hose connected. Drive the car. Then tell us what you experience.

This is kinda a trick question. I already know the answer. I believe you and the rest of the folks following your engine build would be incredibly surprised at the result.

Save The Wave!

 

[Vettefan87]

I don't think you can ever get 0 retard. When you punch it you will see a spike in the retard then level off. When I used to have my 87 GN we used to look for no more than 4 degrees retard. Sometimes top performance comes when the timing is retarded from optimum. If you are only getting 3-6 degrees retard then I wouldn't be too concerned especially if it hits six then pulls back to 3.

Well then maybe my car is a freak of nature, because I get 0 degrees knock retard. I can go check again tomorrow, but I remember craig saying I had no counts of spark knock, and no knock retard and I was getting around 32 Degress of WOT advance.

 

[vetteboy86]

With these mods:



I would say he is far from stock.:L:L:L

Where did you get that Eagle rotating assembly from? Are they pretty good?

I would imagine he purchased through Summit or something. Possibly he could have gotten it through is supplier. That is what he recommended, and also what Mad Mic recommended.

I think it was 850.00 bucks

 

[Edmond]

I would imagine he purchased through Summit or something. Possibly he could have gotten it through is supplier. That is what he recommended, and also what Mad Mic recommended.

I think it was 850.00 bucks

Oh, I thought that you had bought the parts and brought them to him. Is $850 a good price? If my motor looks like it needs a rebuild, I wouldn't want to put it back in there as a 350.

 

[vetteboy86]

No, we ordered the parts together as soon as I figured out what I wanted. I think that is a good price, couldn't find it much cheaper. Like you said, you dont want a big cam, so if you go with the extra cubes, that will give you more torque and hp

 

[Edmond]

Was the transmission rebuilt? Can the stock transmission handle all that power?

 

[vetteboy86]

Not yet, and we will see

 

[rrubel]

Right now the Fuel pressure is set at 46 with the vacuum line unplugged. I also put a heated O2 sensor on the car. Before the car was running lean all the time per the EASE software I am using. The O2 voltage hardly rose above 200 millivolts.

WIth the heated O2 sensor on the car, the car transistions from rich to lean normally now. The O2 sensor voltage now goes from 100 mV to 900 mV like it should.

Ok. Right now I'm getting into tuning up my own 86, trying to pass emissions. Mad-mic told me to check the O2 sensor voltage because he too thinks I need a heated one. Is the 100-900mV the raw data you're seeing using the scan tool? Did the car want to stay in closed-loop all the time? Mine seems to randomly wander between open and closed.

Thanks.
[RICHR]

 

[Vettefan87]

Once his car hits about 160 degrees It stays in closed loop, for as long as we tested it. We did not do any testings longer then id say 10 minutes, and that is being very generous. I think he needs to cut timing back a little since he is running more compression around 10.5:1 I believe and maybe bump the pressure up a little. We need to get some Gtech runs in or something so we can get a baseline to see if the tweaking is making any progress, the "butt" dyno is not accurate enough...although it pulls a lot harder then it did before.

 

[vetteboy86]

When the car is in open loop, the O2 voltage is null, probably because the ECm does not read that voltage until the engine is to operating temps. When my car reaches 165 or so, it will go into closed loop, and the O2 sensor will start reading.

It is my understanding that when in open loop, the tune is rich, only to help with driveability issues.

When I had the normal O2 sensor in, the sensor looked like the car was in open loop all the time even though it was not. I admit, I do have dual exhaust with no cats, so perhaps the car needed this heated O2 for longer then I thought. Anyways, once it gets to operating temp, it should stay in closed loop status. I am not sure where the ECM gets the data, but I would imagine from the coolant sensor. I will have to research that. As far as tuning goes, as long as I am not lean anymore, I will have to do some WOT runs, and then start thinking about new proms

 

[MoeJr]

Craig do you know what your total timing is set at? You probably not gonna want anymore than 32 degrees total with 10.5:1 CR. You are definitely gonna want a custom burned prom and not an off the shelf one. Most aftermarket proms have more aggressive timing curves and may cause spark knock with your CR. Also you may have to slow the timing curve down if spark knock persists.

 

[vetteboy86]

I have no idea what the total timing is, I thought that was set by the springs and weights in the distributor. I know I am running base timing of 6 degrees. right now. I agree, that with a higher compression ratio, the advance shouldn't be as agressive.