Mid-Range Hesitation

Alternator output being that low can help cause all kinds of problems and ghosts.

 

How severe was the power lose?

 

Hmmm...So which is it? 12.4 or 14.2? Heck you could even have a fuel problem. Internet diagnosis is frought with problems.

 

Hi Henry,

Perchance did you notice if the idle speed was a little lower than normal when the you observed that the voltage did not recover until you blipped the throttle?

Are you sure you are checking the codes correctly? If there are no error codes on a 2.7 car you should see the CEL light flash code 4-4-4-4. So you should see something if you check for error codes, even if there are no errors.

 

The era of the 2.7 motronic is right there with the 348 2.7 electronics. They had many ghosts due to electrical connection etc. To compound that was a wonky OBD that worked great on paper but just lacks the robustness of OBD2 and thus it's diagnostic ability not to forget it's wonky interface. I am way less likely to believe OBD. But that said and knowing 2.7 electronics first stop has always been pull the obd codes and view them with a jaundiced eye. Accept but VERIFY. Clean all engine electrical connections bend pins to ensure connections. 2.7's were so bad I routinely like every 3 months just change a fluid and clean all connections. Cleaning was not elaborate. We did all that stuff with Stabilant-22 thinking we had a magic genie but it just did not pan out. There was no magic juice just contact cleaner spray and let dry for a couple hours and reasssembly. Then see if your problems return and start your diagnosis from a known good starting point. Then you can take a close look at electronics or fuel and work your way up those systems. It is a caveman approach but works until the car electronics gets more advanced and you can use other tools to track a problem. Don't forget old school digimeters looking at spark plug parade and raster patterns that can tell you a lot about running and where a problem can be. That simple tech works on anything with a spark plug.

 

Like they said any intermittent problem first thing I do is clean / verify the connections on these cars. Once that baseline is laid down then you can look for the problem if there is any.

 

I'm going to go contrary to the above two posts. I had a similar experience with my car which is a 95 2.7 car. This summer the CEL would flash on for a moment and then go off. Checked codes. They said 1-4 O2 sensor bad. Replaced O2 sensor. Car has been perfect ever since. I'm not about to pull the connector of the ECU and start Fing with it and potentially make things worse for a $60 part. There are times when it is appropriate to just start by replacing a part. Other times when it's more appropriate to look elsewhere. But, as I said before, check for the codes again. You should either get an code telling you what the error is or code 4-4-4-4 indicating no errors stored. That's where you start. Also note that if the CEL went on and off you may have to cycle through the codes. That is to say, OBD I will store the same code multiple times if the error comes and goes. For example, in my case the O2 sensor code was displayed 4 or 5 time before I got the "no more codes display" (series of flashes 2.5 seconds long).

It is important to understand the differences between OBD I and OBD II. If you get a CEL with OBD II the algorithm for the system turning off the CEL is fairly complex, but OBD II will turn off a CEL is the error doesn't reoccur over a sufficient length of time and even erase the code. OBD I systems are generally much quicker to turn off a CEL if the error does not reoccur, but if a code is set it will not be erased from the ECU. It must be cleared.

While not relevant to this thread, I encourage all owners of OBD II cars to download and read the following document to get a better understanding of how OBD II works. http://www.lbcc.edu/attc/documents/OBD2.pdf

 

Henry when it's idling rough it could be a loose connection to a injector. Mine also experienced a rough idle when my idle control valve partly came out of the rubber on the engine side. You might have two of them.

 

It's also a good idea to check the condition and contact of the crank sensors.

 

Curious, you said you cleared the codes which implies that at some point you were able to read them. If so, what were they?

 

Awesome Henry! If the problem was the connections the problems will return. This was a constant time waste and ghost chase the caused me to turn a perfectly good 348 streetcar into a gutted out racecar. It was either sell the car or make it run. It finally ran flawless when every piece of hardware and electronics that did not make the car faster was removed. That had the effect of reducing the electrical load on critical components and leave me with a core of mission critical connections I could manage. If I knew Helms bcak then and his gold kit innovations my life may have taken a completely different path. Today, I might be a waxer!

Anyway, I have had amazing results with the hotly contested controversial gold kit. It just seems to work and make the cars run better and predictability. There is a whole range of connection management techniques like contact cleaner and S-22 contact enhancers. There is a whole range of refurbishment techniques all the way from the cheapest Ernie econo tin pin swap to the SRI/Helms gold kit method. The management techniques were basically a fail. It was constant and unrelenting agony that worked temporarily. Connection refurbishing is the way to go long-term. The job is tedious and demands attention to detail. More attention yields better results. It is such a painful job you only want to do it once. My time is valuable and that means go with the best connection refurbishment method you are willing to buy. It has been SRI for me.

 

Glad you got it sorted Henry maybe another two years before any problems.

 

Just to reiterate on this and what fbb stated

I dont speak much of my background in the industry due to disclosures still in effect.
These cars are amazing bad in the electrical dept. 90% of the things I find bad are a direct cause from bad or less then perfect connections. All roads lead back to fbb