86 spider engine idles but will not rev properly - Alfa Romeo Bulletin Board & Forums
 1Likes
  • 1 Post By ghnl
 
LinkBack Thread Tools Display Modes
post #1 of 13 (permalink) Old 08-22-2018, 07:13 PM Thread Starter
Registered User
 
Join Date: Feb 2012
Location: East Coast
Posts: 47
Question 86 spider engine idles but will not rev properly

So I have another problem with my 86 spider veloce. It starts right away but has a slight misfire? or something every 2-5 seconds. I notice my tach moving up & down. When I try to accelerate the engine bogs down and will eventually rev higher but it begins to pop or misfire at the higher rpms. It seems like the tach is reading below the real engine rpms. The car ran perfectly just a few months ago. I did nothing to it. What could have changed to create this problem? Car has been garaged for the last 5 yrs. The car has been driven once or twice per year.
I'm going to replace the plugs, rotor & cap tomorrow.
Help needed please.
59ARG is offline  
Sponsored Links
Advertisement
 
post #2 of 13 (permalink) Old 08-22-2018, 07:28 PM
BB Janitor
Platinum SubscriberSuper Moderator
 
ghnl's Avatar
 
Join Date: Oct 2005
Location: Mebane, NC
Posts: 16,198
Garage
How old is the gasoline? Today's gas doesn't store as well as it used to. Even a few weeks old seems to give problems.

Try looking under the hood with the engine running on a dark & moonless night (or in a dark garage). Old spark plug wire will sometimes reveal themselves by glowing from electrical leakage. Really bad wires will be arcing & making a light show!
triz likes this.

- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
Mebane, North Carolina


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
ghnl is online now  
post #3 of 13 (permalink) Old 08-23-2018, 05:49 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,675
Back in the day the first thing we would do was put in a new set of plugs. These days modern engines and plugs go 100K miles on a set and we forget that spark plugs can be fickle, so treat your car to a new set.
Eric has alluded to fuel problems. I would add that the fuel filter is a consumable item and changing it is also doing your car a favor. A partially plugged filter or water in the filter can cause your symptoms.
If you only drive your car infrequently then it should be a long drive to get the engine hot and some full throttle accelerations to clean the plugs.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke

Last edited by alfaparticle; 08-23-2018 at 05:52 AM.
alfaparticle is online now  
Sponsored Links
Advertisement
 
post #4 of 13 (permalink) Old 08-23-2018, 06:16 AM Thread Starter
Registered User
 
Join Date: Feb 2012
Location: East Coast
Posts: 47
Thanks to you both, I will be doing a tuneup and replacing the fuel filter later today. I'll keep you posted if I solve the problem. Merci.
59ARG is offline  
post #5 of 13 (permalink) Old 08-23-2018, 08:36 PM Thread Starter
Registered User
 
Join Date: Feb 2012
Location: East Coast
Posts: 47
OK, so i replaced the plugs, rotor & distributor cap. Also changed out the fuel filter and added 5 gal of fresh fuel 100% gas, no ethanol. The spider runs better but it still seems to bog down when I Step on the gas. Changed 2 of the 4 vacuum hoses, 2 more tomorrow. I looked at the engine running in the dark and there was no light show. Does anyone have any other ideas what the problem could be?
Help please! I'm stumped.
59ARG is offline  
post #6 of 13 (permalink) Old 08-23-2018, 08:45 PM
Registered User
 
Join Date: Jul 2018
Posts: 76
Sounds a bit similar to what I was experiencing. I have an 87. My car would not want to go above 25. I'm in the process of changing my whole fuel system. My tank had serious rust, lines inside were also rusty, it would start occasionally and then shut off. The fuel pump was seriously clogged, injector filters were also shot.

Check my thread so you can see if it's similar.
triz is offline  
post #7 of 13 (permalink) Old 08-24-2018, 05:57 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,675
I too had a failing fuel pump on a GTV6 that had stood for many years. The symptoms were that It felt like I had stepped on the brakes above a certain rpm. When I put in a new pump it locked up solid after a few miles. The cheap aftermarket pump that was in it when I bought it would run but not deliver sufficient fuel and the new Bosch ones failed quickly. These pumps have tight clearances and scale from the tank will lock them up.
If you suspect the fuel pump then buy a fuel pressure gauge for about $20 from Harbor Freight and Tee it into the line to the cold start valve. Then rev the engine and see if the pressure holds fairly steady at about 40 psi. If it drops dramatically then the fuel pump is failing or there is a big restriction in the fuel line. I eventually found a good clean tank to replace the one in my car and before that I installed a strainer in the fuel line between the tank and the pump. It had collected a lot of debris each time that I cleaned it.

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is online now  
post #8 of 13 (permalink) Old 08-24-2018, 06:51 AM Thread Starter
Registered User
 
Join Date: Feb 2012
Location: East Coast
Posts: 47
Thanks everyone. Another question. Does the catalytic converter need to work properly? Could it possibly be the oxygen sensor? Might that not be the cause of the engine bogging down? I did drive it over July 4th and the cat got hot and started smoking underneath the car. I had to shut off the engine and let everything cool down. I've never had this happen before. I got home on reduced power but luckily I was only a mile or two from home. Any thoughts here? Could there be a connection?
This is the first time I've tried to drive the car since then.
59ARG is offline  
post #9 of 13 (permalink) Old 08-24-2018, 07:41 AM
BB Janitor
Platinum SubscriberSuper Moderator
 
ghnl's Avatar
 
Join Date: Oct 2005
Location: Mebane, NC
Posts: 16,198
Garage
The way most catalytic converters fail is that they get 'polluted' and clogged. That restricts the exit of the exhaust gases. The worst one I saw (Dodge pick up truck) allowed the engine to idle but it wouldn't rev up any higher.

An over rich mixture will slowly pollute them, leaded gas will do it quickly. A failed O2 sensor allows a slightly rich mixture.

- - Eric
don't read this
~ 1984 Spider Veloce ~
- -~ 1981 GTV-6 ~
Mebane, North Carolina


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.


To view links or images in signatures your post count must be 0 or greater. You currently have 0 posts.
ghnl is online now  
post #10 of 13 (permalink) Old 08-24-2018, 08:12 AM
Registered User
 
Join Date: Jul 2018
Posts: 76
Quote:
Originally Posted by 59ARG View Post
Thanks everyone. Another question. Does the catalytic converter need to work properly? Could it possibly be the oxygen sensor? Might that not be the cause of the engine bogging down? I did drive it over July 4th and the cat got hot and started smoking underneath the car. I had to shut off the engine and let everything cool down. I've never had this happen before. I got home on reduced power but luckily I was only a mile or two from home. Any thoughts here? Could there be a connection?
This is the first time I've tried to drive the car since then.
A clogged cat could cause those symptoms as well. If it got red hot, definitely clogged and any oil can cause a fire!
triz is offline  
post #11 of 13 (permalink) Old 08-24-2018, 09:18 AM
Senior Member
Platinum Subscriber
 
alfaparticle's Avatar
 
Join Date: Oct 2004
Location: Columbia SC
Posts: 12,675
Quote:
A clogged cat could cause those symptoms as well.
Agree!

Ed Prytherch
79 Spider
76 Suzuki GT500
2011 Jaguar XKR

A little government and a little luck are necessary in life, but only a fool trusts either of them. - P.J. O'Rourke
alfaparticle is online now  
post #12 of 13 (permalink) Old 08-24-2018, 06:10 PM Thread Starter
Registered User
 
Join Date: Feb 2012
Location: East Coast
Posts: 47
Well then that might be my problem, the cat converter. That's only a $500 repair. Seems like the hits just keep on coming.
Thanks everyone for the helpful advice. I'll tear into the exhaust this weekend. When I take off the center muffler section and the
cat is exposed, anything I should look for? Good or bad? And yes the cat did get quite hot that last drive. It was a smoking underneath the car.
I'll keep you posted on progress.
Grazie
59ARG is offline  
post #13 of 13 (permalink) Old 08-24-2018, 06:21 PM
Registered User
 
Join Date: Jul 2018
Posts: 76
Quote:
Originally Posted by 59ARG View Post
Well then that might be my problem, the cat converter. That's only a $500 repair. Seems like the hits just keep on coming.
Thanks everyone for the helpful advice. I'll tear into the exhaust this weekend. When I take off the center muffler section and the
cat is exposed, anything I should look for? Good or bad? And yes the cat did get quite hot that last drive. It was a smoking underneath the car.
I'll keep you posted on progress.
Grazie
You could always cut the cat and weld in a straight pipe. That will cost next to nothing.
triz is offline  
Reply

Quick Reply
Message:
Options

Register Now



In order to be able to post messages on the Alfa Romeo Bulletin Board & Forums forums, you must first register.
Please enter your desired user name, your email address and other required details in the form below.

User Name:
Password
Please enter a password for your user account. Note that passwords are case-sensitive.

Password:


Confirm Password:
Email Address
Please enter a valid email address for yourself.

Email Address:
OR

Log-in










Thread Tools
Show Printable Version Show Printable Version
Email this Page Email this Page
Display Modes
Linear Mode Linear Mode



Posting Rules  
You may post new threads
You may post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off

 
For the best viewing experience please update your browser to Google Chrome