At wits end with 86 Carrera troubleshooting - Page 2

ivangene · 07-31-2012, 06:27 AM

check for intake leak - easy to do and IMO a good candidate for this high HC readings

O2 sensor should not effect the HIGH HC #'s

basic tune up items (cap, rotor, plugs, wires, coil) would be good to know condition of

ivangene · 07-31-2012, 06:28 AM

oops...CO% 0.03??

that is too low and may be your issue...lean miss
raise that to 1.0 pre cat reading

still could be intake leak though - check for it

AtomicDog · 07-31-2012, 07:34 AM

Sorry for the delay in response - lots of information to absorb, as well.

Plugs, wires, cap, rotor, and fuel filter are 3k to 5k miles old. I will be checking fuel pressure soon...

The coil is, in fact, a Bosch silver coil. John, is there a sure-fire test to determine whether or not the coil is failing?

The 0.03% CO was the tailpipe measurement, so I don't yet know what it would read pre-cat. In fact, I'm not sure how to get this measurement. What is the process?

Brakes do not feel any different. This wouldn't surprise me, as any vacuum leaks have been present for quite some time.

This week I will replace the O2 sensor, check the coil/swap with my old one, perform a compression test and fuel pressure test, plug all vacuum lines not absolutely required to run the engine, and replace the rest of the vacuum hoses sitting in my garage. Sound good?

Thank you again!

rick-l · 07-31-2012, 07:59 AM

How come everyone is so reluctant to swap out fuel injectors? You can get them flow tested for $25 apiece, get rebuilt ones from here for $45, new similar ones from motorman for $45 or used ones for $30.

ivangene · 07-31-2012, 08:49 AM

there is a plug in the front of the cat you remove to get the readings pre-cat

that plug is very easy to break off so make sure you have all your attention on it and be very gentle and liberal with the lube of choice - work it SLOW in ant out - SLOW dont let it get hot

not that this is your problem, its just the place to set CO% if you have a cat

AtomicDog · 09-02-2012, 09:14 AM

Just performed compression test. Engine was cold and cylinders dry. All cylinders were 160-165#. That's within 3%, so I'm thinking that the platform is sound...

Off to plug vacuum lines.

Chris

E Sully · E Sully's Garage

Compression sounds good. Verify the gap on the new sensors? Pull the connectors and check for resistance just to make sure. New doesn't guarantee they are good. Did you check the AFM with 9V battery after you moved the wipers? Check the AFM temperature sensor?
Just for fun, pull the spark plugs and see if any look different. Carbon from oil, wet from gas, new looking as if it is not getting fuel. Pull the wire connectors off the injectors, get a meter and check the resistance across each one and see if they are consistent. You could also apply V to each one and see if they click open and closed. I bought a used '86 that sat for awhile. 2 injectors were stuck closed. I managed to free them up by spraying with carb cleaner and tapping them while intermittently applying V. Pull the distributor cap and rotor. Do they look good without rub marks or carbon pitting. Do the distributor weights look clean and lubricated, move freely?
I ran mine for 1000 miles with no O sensor and it ran well. Have you removed the oil cap while idling to see if rpm drops? If not that would indicate a vacuum leak. Check the 2 vacuum lines on the cruise control module by the fuel filter are connected.

AtomicDog · 10-19-2012, 05:24 AM

Sorry for the delay in reporting the resolution. Time ran short, so I had my shop handle the rest of the troubleshooting...

Smoke testing showed a massive leak on the #3 intake runner. Once the manifolds were re-sealed, the engine ran well. What was interesting, was that no amount of starting fluid sprayed around the area gave any indication of the leak.

Bodymotion (Ocean, NJ) re-sealed the intake manifolds for a grand total of $847, and had the car back to me in a day. YMMV, but I thought this very reasonable, and would recommend that you give them a try if you need something done.

Thank you for all of the great input. I will still be taking your suggestions to improve driveability, as there is still improvement available.

Chris

db_cooper · db_cooper's Garage

Yep..3.2s like to suck in the intake gaskets. Probably a good idea to replace them from time to time.