'86 GN- Motor breaks up (pops) at 5-10 psi of boost

[groumoutis]

I just had a very similar situation. If unmetered air goes into the engine the car will pop and fall on it's face. I had a small crack is my hose from maf to turbo inlet and air got in once I hit boost and the engine leaned out because of the maf being bypassed. I thought it was water in my fuel At first so I took a sample and found out the fuel was good but at the right angle I noticed the cut/crack is the hose. A intercooler hose would do the same thing except it would go rich instead of lean. Hope that helps.

 

[Chuck Leeper]

"Os volts @ 82 range"......???? And, at only 10# boost??

 

[TurboDave]

"Os volts @ 82 range"......???? And, at only 10# boost??

I wonder if he means 082 or 820??? If 820, that's understandable since the OTC's read aprox 100mv higher than typical scanmaster and other tools readings because of it's internal referance.

 

[jarredsoon]

can someone clarify how to ohm the plug wires
what number onthe meter are we looking for and is there a range of good to bad?

Also can plug wires go bad just all of a sudden??

Thanks

Jarred.

 

[hesermon]

can someone clarify how to ohm the plug wires
what number onthe meter are we looking for and is there a range of good to bad?

Also can plug wires go bad just all of a sudden??

Thanks

Jarred.

Jarred, the exact amount of resistance will vary slightly depending on the quality and length of wire. That is really not too important, what is important is that all wires show similar amount of resistance on the meter. If you have no or significantly less on one wire, you have a bad wire. It is usually either the internal wire has come out of the end piece or the wire is burnt through from touching the exhaust. In the latter case, sometimes you won't see the damage while it is on the car because it will likely be on the bottom of the wire. Often you won't even the spark arcing onto the header because it may only do it at higher rpm's while running down the road.

As to can plug wires go bad all of a sudden: it takes about half a second for a wire laying on a header to burn through enough to cause failure and it is pretty easy to damage the wire end by pulling on the wire instead of the end piece when removing it from the plug or coil. I've seen this a lot when people try to change their plugs without allowing the headers enough time to cool before trying to remove and replace wires.:redface:

 

[jarredsoon]

Hey Thanks for expaining that

Jarred

 

[Sixxshot87]

When I had a popping out the intake (like the engine was loading up on unburnt gas) it was the coil pack. I didn't see anywhere in the post where you said if it was popping out the intake or exhaust. If it is the exhaust you might check the cam sensor. I actually don't think it is the cam sensor or the coil pack based off your O2's though. Im going to take a shot in the dark here and say check your MAP sensor and make sure it is hooked up (powered and has a vacuum line connected to it). If it is running fine at low boost (like off idle and below 5 pounds and then pops out intake I would normally say coil pack). But in this case I say MAP sensor because of how lean you are running in boost. Its like the map sensor is not getting a reading in one form or another and not compensating for the added boost and as a result you will run like normal out of boost but lean out the more you go into any boost. so check your vacuum lines, power to map and signal wire to the ECM. Just a thought

 

[Sixxshot87]

I forgot to mention about the plug wires. I have also had plug wires cause problems but not like what your describing. I hot lapped at the track 1 too many times (23 passes in 2 hours to be exact LOL) and a plug wire melted to the header and grounded out causing a power loss and a slight miss fire. Also do you mean 82mv on the scan tool or 820. If 82 read my first response (super lean) if 820 disregard.

 

[MR PAUL]

e mail me i think i know what the problem is paulvega38@yahoo.com

 

[TurboDave]

e mail me i think i know what the problem is paulvega38@yahoo.com

Enlighten the rest of us. This is a public forum. We try our best to share our expertise here.