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#21
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Its easy to inspect plug colors and condition, also you can figure if its systemic or a particular cylinder along with a compression check
if there is no outliers with these two things then something that effects all cylinders would be highly suspect any MSD components involved here?
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If your not at the table you're on the menu A man who falls for everything stands for nothing. |
#22
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The system uses a Summit Racing billet distributor which is a copy of the MSD Pro Billet. It wouldn't surprise me if they were exactly the same. MSD adjustable rotor, MSD Blaster 2 coil and on the electrical end the vehicle subsystems are powered via an MSD 4 channel solid state relay. The ignition components listed above are about 3 years old.
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-Jason 1969 Pontiac Firebird Last edited by JLMounce; 03-25-2024 at 12:10 PM. |
#23
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In the mean time if you have a laptop for tuning you could download the current tune and have a look at the learn table. If it's crazy high in the wot throttle areas like I mentioned that's a good indicator you have a fuel delivery problem and the unit is trying to cover it. That's one nice thing about these units is the safety they provide for things like that. Keeps you from totally destroying the engine at wot. Not sure if you have changed your compensation limits in your tune but they are typically set at 50 percent which is a ton of fuel. I usually turn them down to 10 percent or less in cruise and idle areas but the wot area I leave at least 25 percent just for situations like that. |
#24
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I do have the ProCal software that I can dig in to the tune. I don't have my learn limits turned down. On the FiTech's the long term trims can only go to 30%. I drive the car in such varying weather conditions and altitudes that it makes sense to let them have some play. I may have caught this quickly enough that it hasn't had much time to significantly alter the long term trims. It's worth a look though.
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-Jason 1969 Pontiac Firebird |
#25
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I had a similar problem with my Sniper. It was a bad injector.
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A new best of 9.135 @ 145.41 71 Lemans Sport. 72 Lemans Sport. |
#26
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Yes, bad fuel pump, bad injector, 02 sensor acting up can all cause EFI to dump more fuel under load or higher RPM causing misfire or loss of power
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#27
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Had some time this afternoon to at least plug in the laptop.
The long term learn values for WOT are all very close to what the VE table is commanding. They are ranging from -5% at 5500rpm to +7% around 4000rpm, but most are within half a percent of commanded value. However, as I said, there may not be enough long term learn at these points as I haven't been hotroding the car much recently, mostly just cruising because the cold roads won't hold that much power. What is happening however is that my cruise to moderate acceleration trims in the 1800-3000 rpm range are all extremely out of whack to the rich side. 35-75kPa load range in that RPM window has learn values over 30% in some places, with the highest values at higher loads. This is where the car is being driven the most and I think this does point to a fueling issue. Considering this is only apparent in this rpm range, I don't believe this would indicate and issue with the oxygen sensor. If that was the case I'd expect learn values to be crazy all over the place.
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-Jason 1969 Pontiac Firebird |
#28
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Have you looked down the barrels and confirmed all injectors are working?
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Will Rivera '69 Firebird 400/461, 290+ E D-Ports, HR 230/236, 4l80E, 8.5 Rear, 3.55 gears ‘66 Lemans, 455, KRE D-Ports, TH350, 12 bolt 3.90 gears '69 LeMans Vert, 350, #47 heads: work in progress |
#29
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But if a fuel pump is acting up, causing EFI to dump more fuel, all injectors could/would be working and not tell you anything by seeing they are all working at idle....
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#30
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Yes, I've verified all injectors are functioning. No injector fault codes either.
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-Jason 1969 Pontiac Firebird |
The Following User Says Thank You to JLMounce For This Useful Post: | ||
#31
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To me, it sounds like an ignition issue.
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The Following User Says Thank You to 65 Lamnas For This Useful Post: | ||
#32
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Have a vacuum gauge?
What kind of timing chain/gear do you have?
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John Wallace - johnta1 Pontiac Power RULES !!! www.wallaceracing.com Winner of Top Class at Pontiac Nationals, 2004 Cordova Winner of Quick 16 At Ames 2004 Pontiac Tripower Nats KRE's MR-1 - 1st 5 second Pontiac block ever! "Every man has a right to his own opinion, but no man has a right to be wrong in his facts." "People demand freedom of speech to make up for the freedom of thought which they avoid." – Socrates |
#33
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I can't be 100% positive, but I believe the timing set is what Comp Cams supplies with their complete timing kit. It's a double roller type. The engine had a 280H in it when I changed out the top end. It had the complete comp kit in it so I'm assuming it had the timing chain as well. I reused as there was no slack in the chain. I always estimated the engine only had a couple thousand miles on it when I purchased the car from the previous owner.
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-Jason 1969 Pontiac Firebird |
#34
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I spent the day working on the car and doing some testing. I wish I had a complete log but for some reason the log function in the procal software or on my handheld is not functioning. Might be something with the laptop I’m using.
Anyhow here are my findings. Fuel pressure is running at 50psi at idle, it should be 58psi. On a quick rev it’s dropping to 40 psi. That’s definitely a problem. Replaced the fuel filter and I honestly can’t say that the old one looked terrible. That clearly wasn’t the issue. I verified all injectors are firing at idle and through the rpm range. Verified timing has not moved. It’s still in sync with the computer. Changed the plugs, two of them showed signs of the porcelain cracking. Most of them read hot and lean, which makes some sense. Inspected the cap and rotor. Both look good with no indication of ionization issues. The adjustable rotor has not moved from where it was originally set. Removed the valve covers and inspected each spring. No outward indication of the outer springs and what can see of the inner springs being broken. None of the polylocks have moved. Finally also conducted a compression test. Engine at 190 degrees, full charge on the battery, throttle wide open. 1: 183 2: 180 3: 190 4: 182 5: 183 6: 180 7: 191 8: 192 What I was able to accomplish today made no difference in behavior. There’s still way too much fuel in the tank to drop it, so I’ll need to drain some of the fuel. I also went ahead and ordered a genuine bosche fuel pressure regulator. I should be able to get to those next week. Hopefully there will be a positive result. If not I’ll move on to checking the springs and inspecting the lifters.
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-Jason 1969 Pontiac Firebird |
The Following User Says Thank You to JLMounce For This Useful Post: | ||
#35
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I don’t know that 40 psi of pressure when it should be 58 is going to cut it under a load.
I mean that’s a 40% reduction in pressure which has to show up as a factor at high firing rates.
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Wernher Von Braun warned before his retirement from NASA back in 1972, that the next world war would be against the ETs! And he was not talking about 1/8 or 1/4 mile ETs! 1) 1940s 100% silver 4 cup tea server set. Two dry rotted 14 x 10 Micky Thompson slicks. 1) un-mailed in gift coupon from a 1972 box of corn flakes. Two pairs of brown leather flip flops, never seen more then 2 mph. Education is what your left with once you forget things! |
#36
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The fact that it won’t hold 58psi at hot idle when fuel demand is at its lowest is why I’m also replacing the FPR.
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-Jason 1969 Pontiac Firebird |
#37
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What is your CR?
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1967 Firechicken, 499", Edl heads, 262/266@0.050" duration and 0.627"/0.643 lift SR cam, 3.90 gear, 28" tire, 3550#. 10.01@134.3 mph with a 1.45 60'. Still WAY under the rollbar rule. |
#38
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Sounds like a possible fuel pump issue. What kind of pump setup are you using? Edit: never mind I see you mentioned dropping the tank so you have an in tank setup. That's good news. Just make sure you get a genuine walbro. Not the cheaper stuff advertised as walbro on ebay. Those seem to have problems and I suspect they are reboxed garbage. I always just order directly from Walbro, I pay more but I know what I'm getting in the box. It's the same stuff all the OEM's use. A trap door would have that swapped out in about 15 minutes, even with a full tank of gas Just sayin. Last edited by Formulajones; 03-31-2024 at 08:46 AM. |
#39
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Good looking pumping numbers for your altitude.
Sounds like you narrowed down the issue to fuel. Most likely the pump wore itself out and won’t pump enough pressure anymore. |
#40
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When I did the top end, I was able to get a rudimentary reading based on deck height, it's around 10.25:1.
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Yeah I'm thinking that's likely it. These numbers are pretty consistent from what I observed the last time I conducted a compression test about 5 years ago. There's a couple cylinders that are actually pumping a little harder. Could be that I've got a new battery in the car at this time.
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-Jason 1969 Pontiac Firebird |
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