I have a few questions:

I have recently been having problems with how well my car runs. When I got it, it had some top end hesitation, around 6k rpm, but ran fine otherwise.

I had an upper heater hose blow, but I did not overheat. When I replaced that hose, I took the alternator off in order to replace the hose. When I put everything back on, the car does not like to cold start.

I then replaced the spark plugs, and found out that 2 plug wires had been mixed up, but I did not here pinging prior to finding this problem. Once I switched the wires, the car starts better, but at idle, it tends to surge about 200-400 rpm, but only when warmed up.

It still has high end hesitation, etc. Also, I noticed that the car runs rich, and not only at idle. I am just wondering why the car is running so roughly since I took my alternator off. Could I have pulled a crucial vacuum or electrical wire in the process?

Thank you for your help

 

need year, model, and modifications

 

Whoops, sorry about that.

Its an 87 rx7. I was told it was bridgeported, but it is running off the ecu with a piggyback chip. The AFM was "modified to adjust the airflow." I am not completely sure yet whether or not it really is, but it has the signature bridgeport sound(brap brap), and it has more power than any stock fc I have driven, and only has a header and conefilter. Anyways, it was running and starting fine until I removed the alternator, and now that I put it back on, its running much worse.

Thank you

 

Oh, and I will eventually get a standalone for it, I just don't quite have the money for it just yet.

 

Did you install a different alternator or change the wiring at all? And even if you didn't maybe something didn't get connected properly, I'd say check your battery voltage at idle and other RPM and regardless double check the battery and alternator connections.

 

I would also recommend checking the connection to your water thermo-sensor on the back side of your water pump. I had a similar problem after my rebuild, running very rich, bouncy idle... turned out this connector was coming loose.

...when this happens, it runs in a fail-safe mode and convinces itself that the water temp is at something like 80 degrees (at all times). So when the water temp gets higher than that, your car will run shitty. I know it seems odd that water temp would effect you fuel mixture, but it is relevant to how your car will idle.

 

Thank you guys for your help.

I did not change alternators, and I put the wires back on correctly.

Thank you for telling me about the water thermo-sensor, it makes sense because the ecu would flow less air if it didnt know what temperature the coolant was.

On a new note, I haven't got to check the sensor plug, but I noticed that when I turn my fuel pump off, the car goes back to normal idle for about 3-4 seconds. I have a walbro, and I think since I put a few bottles of injector cleaner through the car, it may be flowing too much fuel. The exhaust is worse than stock because it is a stock with a pipe cut off and welded shut

Am I right in saying that it could be running too rich since I can turn my pump off and idle goes back to normal?

I was thinking that if it was just too much fuel, I was going to get a borla exhaust anyways, so that would lean out the mixture by flowing more air, correct?