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Discussion Starter · #1 · (Edited)
I've been troubleshooting a number of issues with the car - coughing and sputtering at idle, popping in the exhaust during acceleration along with surging issues, driver's side 1/3/5/7 bank running richer than passenger side 2/4/6/8 bank, driver's side cat glowing red on occasion (assuming excess fuel dumping), exhaust gas on DS seems to be pushing more volume out than PS, total lack of power while accelerating, and hideous gas mileage - less than 10 mpg on my last tank of gas!

I replaced the ICM (also did spacer cooling mod), installed 2 new O2 sensors, replaced plugs and wires, suction cleaned cats with shop vac and MAF cleaner (sprayed into / sucked through 02 bungs) and verifying unobtructed, free flow of air through both cats, suction cleaned both sides of dual exhaust out through muffler and exhaust pipe (unbolted from cats), cleaned Optispark, popped off valve covers on both sides and did running valve lash adjustment on all valves, ran motor flush and changed oil with full synthetic 10W-40 and new K&N oil filter, topped off the gas and added Lucas injector cleaner. Overall, the car is running significantly better than it was a few days ago, but it's still not running 100%.

So, I dug around the garage to find my fuel pressure gauge (which I probably should have done a few days ago...), hooked it up to the Shrader, and noted some improper readings. From my research on this Forum and various Google links, these readings might be indicative of a fuel pump going bad. The stock Fuel Pump Regulator appears to be functioning properly. Check out my readings and tell me what you think the problem(s) may be:

- Key on -> Fuel pressure rises to about 42 - 43 psi.

- Start up and running -> Fuel pressure drops to about 38 - 39 psi.

- Running then popping off the FPR vacuum connection -> Pressure jumps from about 38 psi to about 46 psi (I understand you're supposed to see a jump in fuel pressure when popping off the vac line, correct?).

- Throttling up from idle to WOT -> Opening up throttle initially to WOT the fuel pressure jumps momentarily to about 45 psi, then falls back to about 38 psi while holding WOT.

- Throttling back from WOT to idle -> Fuel pressure drops from 38 psi to 35 psi when the throttle is released, then it returns quickly to about 38 psi.

- Key off -> Fuel pressure drops rapidly to about 33 psi, then increases slowly to 43 - 44 psi about 5 minutes after engine shutdown.

Interesting readings, huh?! I would sure appreciate any feedback, sage advise, wisdom and expert diagnosis from the forum to help me resolve this issue. Thanks in advance.
 

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Sounds exactly like what I was going through but I replaced many more parts chasing the issue. There's only 3 things I would recommend checking...........

The OPTI or the OPTI or maybe the OPTI
 

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Discussion Starter · #5 ·
The Opti is always a likely culprit, although I just replaced it less than 10 months ago. The AC voltage reading on the Opti Harness (Pin B, I believe) to ground indicates proper signal from the Opti portion (pulsing AC voltage about 2 - 3 VAC, thereabouts). Checking the Coil Pins A & D to ground, I get about 13 VDC, so my 10 month old MSD Blaster coil, ignition fuse and wiring between should be fine. I've run the spark plug checker between every spark plug and boot and it appears that I have proper spark on every one.

It's entirely possible that the high voltage "spark" portion of the OptiSpark might be operating erratically, carbon or gunk on the rotor blade and/or plug contacts, or whatever. Nothing surprises me anymore when it comes to the OptiSpark... Any good tips or tricks on testing the Opti other than Shbox.com guidelines and spark gap testing? I'd hate like hell to think I have to yank everything apart again and replace a relatively new Opti unit. cwm6
 

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Discussion Starter · #6 · (Edited)
Here's some new info. I was reviewing my initial post and all my readings and it struck me that the the FRP could be part of the problem - based on the 46 psi reading when I pulled the vac line off the FPR. Thinking about it, 46 psi is about what the fuel pressure reading should be normally vs. the 38 psi I was seeing with the car running and vac line connected.

I decided to test my theory, hooked up the fuel pressure gauge, disconnected the FPR vac line and plugged it. Key on pressure was 44 psi, car running was 46 - 47 psi and throttling it up and down didn't change the line pressure by more than about 1 psi. That would more of a normal operating pressure scenario than the screwy up and down pressure readings that I outlined above, correct?

So, I taped the Fuel Pressure Gauge to my windshield, took it for a drive and noted that the line pressures remained fairly constant around 46 psi during acceleration, deceleration, constant speed driving and idling - with the FPR vac line disconnected and plugged. The car did accelerate much better than before and had less sputtering and misfiring in the exhaust, but it still has that feeling like it's running 'off-balanced' - almost like it's running on 7 of 8 cylinders sometimes.

The other issue that I want to bring up is that the car "surges" when you're braking lightly and coming to a stop. Once stopped at red light, for instance, the car kind of pulses and surges like it wants to move forward while your foot is on the brake. When it does that, the headlights will surge in intensity, dimmer, then normal brightness, dimmer, then normal brightness - dimmer during a surge or pulse, then normal brightness between surges. Very odd. Again, this could be Opti-related in some way. Any thoughts? Lots of crazy stuff going on here lately with my 9C1. :confused:
 

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My readings - 43 PSI primed, 36 idle, 45 w/o FPR, 35-41 driving.
 

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Discussion Starter · #8 ·
Thanks for the comparative readings. Maybe the problem I'm having isn't related to fuel pressure, since your readings are very similar to mine - and I'm assuming your car is running fine.

Maybe the problem is Opti - Opti - Opti. I just ordered a brand new CMS OptiSpark off of Ebay for about $85 delivered. Great price! I read some good reviews about their Opti units this evening, so I figured I'd try one of these out and see what happens. I've had sh!te for luck with the stock GM Optis (2 of them in 2.5 years) and paid about $140 - $150 for each of them. $85 sounds great to me and they come with a mfrs. 1 year warranty. Well worth the risk, IMHO.
 

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Thanks for the comparative readings. Maybe the problem I'm having isn't related to fuel pressure, since your readings are very similar to mine - and I'm assuming your car is running fine.

Maybe the problem is Opti - Opti - Opti. I just ordered a brand new CMS OptiSpark off of Ebay for about $85 delivered. Great price! I read some good reviews about their Opti units this evening, so I figured I'd try one of these out and see what happens. I've had sh!te for luck with the stock GM Optis (2 of them in 2.5 years) and paid about $140 - $150 for each of them. $85 sounds great to me and they come with a mfrs. 1 year warranty. Well worth the risk, IMHO.

How's your opti vent/vacuum harness? A non-functioning one will eat optis like I eat chicken wings. Were those delco optis new for that price? (seems way low for a genuine part) A real delco runs in the neighborhood of $350. Some companies (especially on ebay) are good at wording their ads to make you believe they are OEM parts, when in reality you're getting a cheap knock-off. I wouldn't waste my time with those cheap optis. Have had my fair share of experience in that area. Can't speak for the brand you're purchasing, but you usually get what you pay for when it comes to optis.... Just my opinion.
 

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You should have read my sticky post. You're wasting your $ on those cheap eBay or other opti's. I went through 2 opti replacements and 100's of $ in other parts [including fuel pump and FPR] before doing the opti again and BINGO!

Check the cap and rotor [arching inside, loose rotor screws] and as mentioned above, the opti vent harness for improper operation. Sounds like you're using some cheap opti's and it's a waste of time IMHO.

Good Luck!
 

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Discussion Starter · #11 ·
Thanks for the feedback on the Optis and the vent hoses, guys. The larger vent hose still has good suction (holds a small piece paper with vacuum) and the one-way check valves still work, smaller line to intake is clear and air free flows. Probably would be a good idea to buy a new one anyway and replace the old one - as long as I'm spending money... ;) Any good sources for reasonably priced Opti vent harnesses?

Regarding the Optis, they were both Delco units. Bought them from 2 different private sellers off Craigslist. Came in mfrs. packaging, but not sealed. May have been reman'd possibly. I guess I'll see what the new CMS OptiSpark looks like when I get it. $85 is worth trying it out and seeing how long it lasts.

BTW, does anyone have an extra LT1 AFPR they want to sell with for a decent price (Holley, Aeromotive or Metco kit)? Let me know.
 

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I guess I'll see what the new CMS OptiSpark looks like when I get it. $85 is worth trying it out and seeing how long it lasts.
Yeah, keep telling yourself that when you are taking your water pump off AGAIN after that Opti craps out on you in a few months, if that long.

Your fuel pressure readings look totally normal, and it looks like your FPR is working fine, as well. A glowing cat is never good, its likely ruined. When the engine is idling, do your get distinct pulses of exhaust out of both pipes, or does it just wheeze out?

Do you have a CEL?
 

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Discussion Starter · #13 · (Edited)
Yeah, I'm getting to be a pro at pulling water pumps and swapping Optis! Fun, fun, fun!! I'm living in Opti denial, I guess...

The DS cat is probably shot, as you've indicated. Get fairly regular pulses through it - until it 'hiccups' from an opti misfire or whatever is causing it. Again, DS exhaust seems to be pushing more exhaust gas out than the PS exhaust pipe. Car has a true dual exhaust system, so no crossover pipe between the sides for scavenging the opposing exhaust bank.

Just got the car NYS inspected before the problems hit, so I'm thinking about gutting the cats for now then replacing them before inspection time next year. That could possibly fix the issue if it isn't being caused by the Opti. It would at least eliminate poorly functioning cats as part of the problem, in any case.

I think your fuel pressure assessment is correct. Ran the car down the road with the vac line attached this time and fuel pressures seemed to be OK, albeit perhaps a little bit to low side.
 

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Discussion Starter · #14 · (Edited)
Gutted the cats this afternoon and now have nice even exhaust output on both sides. The car is running considerably better now, although still running a little off-balance. An ocassional misfire and pop here and there, but nothing like before. I'd say she's running about 89% now.

I'm going to do another set of Opti flush, soak, unpowered spin and drain cycles with 91% isopropyl alcohol, then vacuum suck the Opti clean and dry with a shop vac through the vent ports on the bottom, and then through the 4 pin Opti socket on the top and through the coil socket, as well. If it's wet and gunky inside and not too far gone, I've found that a set of the Opti flush and drain cleanings will get the Optispark functioning as well as can be expected without pulling the unit to repair or replace.
 

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Gutted the cats this afternoon and now have nice even exhaust output on both sides. The car is running considerably better now, although still running a little off-balance. An ocassional misfire and pop here and there, but nothing like before. I'd say she's running about 89% now.

I'm going to do another set of Opti flush, soak, unpowered spin and drain cycles with 91% isopropyl alcohol, then vacuum suck the Opti clean and dry with a shop vac through the vent ports on the bottom, and then through the 4 pin Opti socket on the top and through the coil socket, as well. If it's wet and gunky inside and not too far gone, I've found that a set of the Opti flush and drain cleanings will get the Optispark functioning as well as can be expected without pulling the unit to repair or replace.
OMG!

You've likely ruined an opti or 2 already with that procedure.

I can't stress enough, get an ACDelco opti or keep up the nonsense.
 

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Discussion Starter · #16 · (Edited)
I can understand that putting any kind of liquid inside an Opti-Spark unit might seem counter-intuitive - even downright insane, perhaps!

I've had a lot of experience using alcohol to clean virtually anything and everything. I'm an ex-Navy Submarine Sonarman and I've used 90+% isopropyl alcohol for over 30 years to clean all sorts of electronic, electro-mechanical and optical components - always with excellent results.

From what I've seen personally and what I've read on the forums and around the Net, the majority of Optispark failures are caused by moisture intrusion, resulting in rotor / contact corrosion and optical sensor failure. High grade alcohol removes water, first and foremost. It's also very effective at breaking down organic contaminants, bio-films, carbon build-ups and sludgy deposits that may build up inside an Opti-spark unit over time.

If I was to show you the color of the "flushed" alcohol that came out of this particular Opti after the first soak, spin and drain cycle, you would be shocked. I was surprised at how much contamination builds up inside a 10 month old Opti-spark. I have a picture of the flushed alcohol from my 3rd alcohol soak, spin and drain cycle sitting next to a bottle of fresh alcohol. There is still a noticeable difference in the coloration, comparatively speaking. So, there's still crap in there, even after 3 flush cycles.

What I can tell you, for sure, is my alcohol Opti-flush technique brought this particular Opti back from a near-death state. Let me preface this post with a little background info. Two weeks ago before I posted this thread, the car was in an intermittent no-start / start-run-and-die state. The first flush brought it back to the point where the car would start and run, albeit fairly rough. That's when I figured there might be other issues, like the ICM, fouled plugs (which they were), replaced spark plugs, wires, 02 sensors, etc. Still running fairly ragged, I posted this thread to try and figure what the other potential issues might be.

In the interim, I did a 2nd Opti-Flush cycle and the car ran significantly better. Gutted the cats yesterday and estimated the car to be running about 89%. Did a 3rd Opti-flush cycle today, the flush alcohol still showing some discoloration from contaminants, but much lighter than the first and second flushes. Car was running about 94%.

Did some more in-depth research last night and today on the Opti Vent Harness. Compared the stock pics to my OVH today and found that my vent hose was actually not stock, but rigged up with 2 one-way check valves - had no vacuum restrictor valve, just a 2nd check valve. Both check valves work fine, although not having the vacuum restrictor valve could possibly be the root cause of my previous Opti-Spark failures.

Since I am a bit of an inventor and re-engineer, I fabbed my own vacuum restrictor valve, picked up a new Dorman check valve and created my own Opti Vent Harness based on my research of the stock OVH. I've got some pics of my prototype "Opti-Clear" Opti Vent Harness that I'll post up here. The car seems to like my new OVH, so I'll give her a 95% running condition now.
 

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I can understand that putting any kind of liquid inside an Opti-Spark unit might seem counter-intuitive - even downright insane, perhaps!

I've had a lot of experience using alcohol to clean virtually anything and everything. I'm an ex-Navy Submarine Sonarman and I've used 90+% isopropyl alcohol for over 30 years to clean all sorts of electronic, electro-mechanical and optical components - always with excellent results.

From what I've seen personally and what I've read on the forums and around the Net, the majority of Optispark failures are caused by moisture intrusion, resulting in rotor / contact corrosion and optical sensor failure. High grade alcohol removes water, first and foremost. It's also very effective at breaking down organic contaminants, bio-films, carbon build-ups and sludgy deposits that may build up inside an Opti-spark unit over time.

If I was to show you the color of the "flushed" alcohol that came out of this particular Opti after the first soak, spin and drain cycle, you would be shocked. I was surprised at how much contamination builds up inside a 10 month old Opti-spark. I have a picture of the flushed alcohol from my 3rd alcohol soak, spin and drain cycle sitting next to a bottle of fresh alcohol. There is still a noticeable difference in the coloration, comparatively speaking. So, there's still crap in there, even after 3 flush cycles.

What I can tell you, for sure, is my alcohol Opti-flush technique brought this particular Opti back from a near-death state. Let me preface this post with a little background info. Two weeks ago before I posted this thread, the car was in an intermittent no-start / start-run-and-die state. The first flush brought it back to the point where the car would start and run, albeit fairly rough. That's when I figured there might be other issues, like the ICM, fouled plugs (which they were), replaced spark plugs, wires, 02 sensors, etc. Still running fairly ragged, I posted this thread to try and figure what the other potential issues might be.

In the interim, I did a 2nd Opti-Flush cycle and the car ran significantly better. Gutted the cats yesterday and estimated the car to be running about 89%. Did a 3rd Opti-flush cycle today, the flush alcohol still showing some discoloration from contaminants, but much lighter than the first and second flushes. Car was running about 94%.

Did some more in-depth research last night and today on the Opti Vent Harness. Compared the stock pics to my OVH today and found that my vent hose was actually not stock, but rigged up with 2 one-way check valves - had no vacuum restrictor valve, just a 2nd check valve. Both check valves work fine, although not having the vacuum restrictor valve could possibly be the root cause of my previous Opti-Spark failures.

Since I am a bit of an inventor and re-engineer, I fabbed my own vacuum restrictor valve, picked up a new Dorman check valve and created my own Opti Vent Harness based on my research of the stock OVH. I've got some pics of my prototype "Opti-Clear" Opti Vent Harness that I'll post up here. The car seems to like my new OVH, so I'll give her a 95% running condition now.
I would say good job! Keep the experiments coming until you get 100%! :D I am just curious what would be the color of isopropil if you flush a brand new Opti.
 
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