Still trying to get my ride going. I set timing last night and checked fuel pressure (BTW the vacuum controlled FPR is awesome!!), and it ran like crap. I drove it home and put the timing light on each plug wire to see if they all were firing. Sure enough, when I hooked up the timing light to the no 5 wire, there was no light. What could cause this other than a bad spot in the dist. cap? What is the worst it could be? Thanks.


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91RS convertible 355 TBI 65# inj. custom compcam grind .480/.480, Edelbrock TBI manifold, open element, hedman hedders, Y-pipe, cheap cherry bomb muffler, Hypertech cop car thermomaster, Accel coil, wires. 2.02/1.6 cast iron heads. Engine specially made by Pflugerville machine shop. Forged bottom end, balanced. Coming soon: Vacuum controlled FPR, better exhaust, Torque converter, DIY PROM, bigger TB.

 

Bad plug wire, shorting plug wire against something (is the wire close to ANYTHING and/or shorting against something, cracked???) REAL bad spark plug with weak coil (no ground tip on plug, broke off, fouled?), bad cap, bad rotor, bad cap/rotor combination, VERY bad distributor phasing, but I doubt that one.

That's about all I can think of. If I were you, I'd pull the cap + rotor and just replace and then check the intrenal resistance and condition of all your plug wires and replace all the plugs, too. Don't cost much...


[This message has been edited by fast_broker (edited November 27, 2001).]

 

JRoy, I agree, it's got to be something simple. By the way, where did you run the vac. line from that goes to the regulator? Did you just bolt it in, or was there another setting you had to change- like timing, programming, etc? Is the regulator externally adjustable, like, say, a JET unit? I've been considering putting one on my car recently, because my 350 injectors run way too rich during warm up.

 

That vac AFPR may be the cause of your problem, if your problem is a fuel-fouled plug....

 

No light on that wire means no current passing thru it. Make sure the #5 cable is connected to the cap AND spark plug. If the light comes on then you found the break in the condutor. If the light does not come on, check the condition of the distributor, if ok then replace the wire since it has a broken conductor.

If wires are old replace the whole set.

 

F#@#%@!! Well, I replaced cap and rotor, checked spark plugs and wires, and it still was misfiring! I took it to a shop and they told me that there was a fuel line not tightened all the way and that is why it wasn't firing. I got it back from the shop (they didn't charge me, shoulda been my first clue), and it STILL runs like S#!t and is still misfiring!! What is going on?? I am about to set my car on fire and collect insurance. I've been working on this POS for a year now!! Someone help me out!

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91RS convertible 355 TBI 65# inj. custom compcam grind .480/.480, Edelbrock TBI manifold, open element, hedman hedders, Y-pipe, flowmaster single chamber, cop car chip, Accel coil, wires, vacuum controlled FPR. 2.02/1.6 cast iron heads. Engine specially made by Pflugerville machine shop. Forged bottom end, balanced. Coming soon: , Torque converter, DIY PROM, bigger TB.

 

Pull the #5 plug.. Bet ya the gap is closed on it.

Kat

 

You checked the plugs and wires I assume they passed since you didn't mention that you replaced them.

Did you reinstall the wires on the cap in the correct firing order? If not the engine will sound like it's missing?

What was the condition of the #5 plug, please describe. Was there oil on it? Do you know what you are looking at and what to look for?

A good chilton's book has a chart with photos of how to assess plug condition.

If you narrowed it down to #5 and you are too cheap to buy a new set of wires and plugs, then some of the smaller auto part shops (ones that sell to mechanics) will sell you wires individually. Buy one wire and one plug. gap the plug to specs .035" Don't be surprised when you start missing again on a different cylinder. I doubt you are the original owner, so how do you know when the wire set was last replaced?

Your problem is simple and so is the solution. If you still have a miss after replacing the wires and plugs. do a compression test, #5 is easy since it's on the drivers side. Check #s 1, 3, 5, & 7 to establish a benchmark. Consult a manual for the acceptable values. IF #5 is out of spec. ie, compression too low that is the source of your miss.

You could do test when you are replacing the plugs to save time, but I am assuming you do not have the tool or an air compressor.
If it is indeed a miss due to low compression then it could be the rings, blown head gasket, burned valves. Hopefully it is not. The condition of the #5 plug that is in there right now will reveal alot of answers to the condition of that cylinder.

As an aside I had to replace the wire set in my '91 SHO EVERY year, since the heat would get to them.

 

I just read your mods...

HEADER HEAT is the #1 killer of spark plug wires!!! I would check all your wires to make sure.

I invested some extra $ into boot and wire protectors, after I lost a set of MSDs on my '88 due to to header heat.

 

Swap some plug wires from cylinder to cylinder and see if the problem follows the wires. If not, probably the plug. IMO, just replace the cap, rotor, wires and plugs. Sounds like it has been a while and the mileage/performance increase should pay for the parts anyway.

 

Cap and rotor are new, engine is brand new, plugs and wires are brand new. I tried switching wires and looking at the timing light and it seemed like it would start to fire, but then I saw nothing. I wonder if more than one wire is heat damaged. How do I check to see if the wires are damaged by heat? I don't see any visible wear, but I'm assuming that heat can damage the inside.

By the way it isn't the no. 5 cylinder, it is the cylinder on the front passenger side (#2?), and I also found that the # 8 isn't firing either. I might try replacing the plug wires and see if that fixes it. Before I do, can someone tell me the best way to check a wire? Is there some sort of continuity test I can do? How? I have a multimeter.

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91RS convertible 355 TBI 65# inj. custom compcam grind .480/.480, Edelbrock TBI manifold, open element, hedman hedders, Y-pipe, flowmaster single chamber, cop car chip, Accel coil, wires, vacuum controlled FPR. 2.02/1.6 cast iron heads. Engine specially made by Pflugerville machine shop. Forged bottom end, balanced. Coming soon: , Torque converter, DIY PROM, bigger TB.

 

Oh yeah, one more thing. If I am running very rich, could that be a problem. I am using the vacuum FPR, but I am using the spring that came with it.

 

You need to test resistance with a multimeter tool. Remove suspect cable(s) set the tester to ohms put a probe on each end of the wire you should have a value. If your reading is "zero" then there is no resistance (continuity) and the wire is caca. you can try to find where the "break" is buy proging into the sleeve of the wire if you start to get readings you found where the cable went bad.

My #8 wire went out on mine due to heat from headers. at the spark plug end about 4 inches from the plug boot I started to get resistance.

The passenger side will take the most "heat" because of all the crap obstructing that end of the engine A/C, smog pump, heater hoses.

When you get new wires get ones with angled boots so you can route the wires away from the headers, also heat sleeves will help the wires live long healthy lives. a good spark plug loom is essential too for holding the wires place if you have center bolt heads SLP makes a pretty cool loom set that mounts to the center bolts.

 

JROY, I have the cure for the "too rich" with the vAFPR. A new spring. The stock non-adjustable FPR spring is too weak, the one that came with the vAFPR is too strong. (Sound like a nursery rhyme?). I found one that is just right. I am attaching a link to the topic so you can order one. Unfortunately my regular e-mail is temporarily down due to Excite@home's bailing on the internet. You can use my dial-up e-mail address which is ask-tds@msn.com. Or call me. I still have a few springs available for $4 including s&h. Lon https://www.thirdgen.org/messgboard/...ML/001842.html

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90 RS Convertible
Owner: Top-Down Solutions
(626)369-0040

http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

 

Seems like it was multiple spark plug wires. I put the timing light on one, started the engine, and the light didn't come on. Then I jiggled the wire, and the light came on. This would explain why when I swapped wires, I saw the light come on some. I was changing the position of the wires to where it completed the circuit. Thanks for the help, guys. New wires, wire loom, and heat shielding for me! Man, I should own stock in summit.

 

By the way, Lon, I would like one of those springs. Where do I send the check?

 

I'd buy different/better wires, BTW...

 

Which would you recommend? I have the Accel 8mm spiral core right now (The kind you have to crimp and add the boots, which may have been my problem all along). Let me know what wires you run. I plan on making a call to Summit this weekend. Lon are you out there? I tried that alternate e-mail, but it didn't work.

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91RS convertible 355 TBI 65# inj. custom compcam grind .480/.480, Edelbrock TBI manifold, open element, hedman hedders, Y-pipe, flowmaster single chamber, cop car chip, Accel coil, wires, vacuum controlled FPR. 2.02/1.6 cast iron heads. Engine specially made by Pflugerville machine shop. Forged bottom end, balanced. Coming soon: , Torque converter, DIY PROM, bigger TB.

 

MSD Super Conductor 8.5 MM P/N 31359
Set is cut to fit small block Chevy.

Lowest resistance cable on the market!!!

Be sure to order the wire separators
MSD P/N 8841

 

My e-mail crashed Monday at noon when Excite@home pulled the plug on my ISP. I still don't have e-mail back up throught my ISP yet, so I've set-up a web based one in the meantime. E-mail me at topdownsolutions@yahoo.com.
My Address to send for a spring is:
Top-Down Solutions
PO box 5601
Hacienda Heights, CA 91745

I'm going to update my member profile now. Sorry for the confusion. It's been a hectic week here. Lon

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90 RS Convertible
Owner: Top-Down Solutions
(626)369-0040

http://www.taskerinc.com/gs3/profiles/Lon_profile.htm

 

The MSD wires are nice but also succeptible to heat damage, especially the boots. If you are SURE that you can route them properly and/or shield them, get the MSD Supers...

I usually use and recommend plain-old Blue Max wires. Moderate resistance and last a while. They plain work, are reliable and don't cost much. what could be wrong with that?