Surge & Sputter, Rough Idle Continuous Problem

[gsgnnut]

My engine is original and never been opened. I've had similar idle problems through the years. Once it was the IAC. Got a new GM IAC problem solved. Another time, I had 3 loose intake bolts near the egr ports. torqued them down greatly improved idle. Also check EGR valve. If original its probably got a blown diaphragm and leaking. MAF can also cause strange Idle problems. Ive also seen bad TPS sensors and misadjusted TPS sensors cause poor idle. Often the SES light will store codes that you can easily readout that can help you narrow it down. Last, chase down all the vacuum lines. Original lines get porous, soft/hard and leak which causes all kinds of problems. Make sure if you have a K&N you have the AT sensor plugged in and installed in the duct before the MAF.

 

[TommyV8]

My car was doing this recently. I had it checked for vacuum: 9 inches. Not good. The guy I took it to chased down a few vacuum leaks and adjusted the fuel pressure. It is now pulling 16 inches of vacuum and runs a lot better at idle and part throttle, no more sputtering or surging.

 

[getdowngranny]

Have you checked out the site: http://www.vortexbuicks-etc.com/troubshootgeneral.htm? It has LOTS of good info on it. Also, you would need a tester made by Caspers I think. When mine started acting weird ignition wise, I bought a TR6 from Bob Bailey. The ability to use it for troubleshooting made the purchase a no brainer for me.

But back to your problem. Once you change all the hoses, check your fuel pressure, O2 sensor, MAF (especially), intercooler hoses, Headers/gaskets, etc. Then post up what your scanmaster numbers are on every item which might clue someone in. What are the O2 numbers when this happens? What are the high BLM's? What does the IAC number look like? Post it all and we can figure it out.

X2. Great advice here.


Sent from my iPhone using Tapatalk

 

[MauDeuce50]

Good stuff guys, I can't thank y'all enough

 

[LEW_86]

Had the same problem, changed out my coil and ignition module which fixed the problem. The ignition control module that I took out had a crack in it.

 

[MauDeuce50]

Had the same problem, changed out my coil and ignition module which fixed the problem. The ignition control module that I took out had a crack in it.

Ok thanks a lot, i will do that!

 

[LEW_86]

any updates on your issue?

 

[MauDeuce50]

any updates on your issue?

Changing vac hoses today, ill let u know when im finished

 

[Hause]

Subcribed

 

[Frederick]

I was having similar problems with my 87 T . Read somewhere about the fan delay relay. I removed the little trouble maker and the idle is much better. When I broke the relay open the parts inside were all corroded. Why or how this messes with the idle, I have no clue. I even asked Dennis Kerban and he was uncertain that it could cause the trouble.
Try it you might like it! The part isn't really needed anyway.

 

[MauDeuce50]

I was having similar problems with my 87 T . Read somewhere about the fan delay relay. I removed the little trouble maker and the idle is much better. When I broke the relay open the parts inside were all corroded. Why or how this messes with the idle, I have no clue. I even asked Dennis Kerban and he was uncertain that it could cause the trouble.
Try it you might like it! The part isn't really needed anyway.

Wow, hopefully that is the case

 

[LEW_86]

Always try the cheapest route first or whatever is readily available hope you get it sorted out soon

 

[MauDeuce50]

Always try the cheapest route first or whatever is readily available hope you get it sorted out soon

Haha agreed, thanks me too!

 

[John De Lorenzo]

I own a 1987 Grand National and when I start it cold it idles decent for the first 20-30 seconds. Then the engine surges, sputters, and continues to do this 4 or 5 times. Sometimes the engine even stalls. In fact, if you start it cold and immediately take off driving the engine will stall. This is not a problem when the engine is warm. Also when you step on the accelerator there feels to be a split second lag.

The spark plugs, spark plug wires, throttle position sensor, air control valve, MAF, and oxygen sensor are all new and work fine. Alternator and fuel pump work fine as well and mechanic cannot find any problems with the computer.

I am at my wits end regarding this problem for more than one dealer and mechanic have tried to repair the problem and cannot do so for they cannot find anything wrong. Please help. Thanks.

I have the same exact problem Let me know the progress if any Thanks