dirtycleansound

I have a cam and bolt 98z28 I recently purchased. It was running crappy but running (back firing) until recently. Now it won't stay on at idle or low rpms. Previous owner said it needs a tune, coils, and injectors. I'm sure one or all of these items are causing it to backfire/not idle. Where should I start in diagnosing it to determine the problem and if it truly needs coils and injectors. Prev owner also mentioned it was too powerful for stock tensioner pulleys and needs and aftermarket one. Could that be the cause it running poorly?

wannafbody

iTrader: (2)

Most likely it needs the fuel tables corrected for the larger cam.

dirtycleansound

is that done in the tune or hardware?

wannafbody

iTrader: (2)

Tune the computer by laptop.

dirtycleansound

Is it hard to do a tune yourself? Any good resources ?

jetech

Sounds to me like the p.o. didn't know what he was doing. Too powerful for stock tensioner pulleys. The pulleys will be fine they will work with boosted H.P.!
It doubt it really needs injectors if it is a cam / bolt on car. You will find out when you get it tuned if it needs more fuel. Any idea on what cam has been installed? Makes me wonder if it was installed correctly

dirtycleansound

I'm not sure of the cam specs.
I don't believe the cam was not installed properly. Thing is when I originally got it a few weeks back it was idling just fine and running decent despite some intermittent backfiring. I drove it 30 miles home even. Then a few days after when I would take it for a short drive it would start hesitating while at idle. Kept getting worse and worse. Now it won't even stay on at all unless I get it throttle. Feels like it's not getting enough fuel. Here is a video... I have to give it like half throttle for it to barely stay running. Seems to be something something beyond a tune or it wouldn't get progressively worse, right?

jetech

The video does make it sound like it isn't getting the required fuel. Can you check the fuel pressure at the fuel rail? Water in the gas?

1998 t/a

iTrader: (3)

A lot going on here but we need to know what the codes the car is throwing to accurately fix the issue. I have some suggestions from just having done heads and cam on my 1998 and here are some things you should definitely do...

1.) Get higher flowing injectors, you need something in the 36lb range or higher (depending on future mods) should do just fine. I went with FORD 42lb injectors on my setup, a budget friendly option.
2.) You will need an aftermarket fuel pump, either buy and install them to your current pump OR WS6Store has a complete drop in unit for 1998's with the steel tank
3.) Get a Dyno Tune to clean everything up

If the car is throwing codes and you are getting misfires on any of the cylinders, for example, misfire on cylinder 1, take cylinder 1 coil swap it with cylinder 2 and if you get a misfire on cylinder 2 you have a bad coil pack. Honestly, my car has 110k miles on it and i used stock coils with no issues so chances are the coils are fine. I really think your issues are fuel related and you should at least start at the injectors and fuel pump.

dirtycleansound

very helpful. Thank you !!!

I believe you’re right. I’m going to check fuel pressure/make sure MAF is clean next and go from there.

dirtycleansound

Ok so I plugged the tester to it. Got codes P0200 (Injector circuit open) and P0101 (Mass Airflow). It also pulled code P0118 (engine coolant temp sensor) This last code P0118 it was showing when I first bought the car. I know it's not overheating and I know it's not the sensor because previous owner recently replaced the sensor. I think I may have to do with wires going to the sensor...

Anyways, I believe P0200 and P0101 are why it's running like ****. Was thinking about starting by cleaning out the MAF. Any thoughts or ideas about what else I should do in terms of diagnostics ?

jetech

All codes need to be looked at for sure. I would consider looking at P0118 first. Is your pcm going into closed loop? Symptoms of a P0118 could include: 1. Very poor fuel economy 2. A no start condition 3. Vehicle may start, but run very poorly, blowing black smoke, running very rough and misfiring. Watch this video check it @ 6:00. Read this more good info

1998 t/a

iTrader: (3)

clean the MAF see if that does anything. My money is still on injectors. Shoot some starting fluid down the intake see if it improves. This is all fuel related. Faulty ECM is slim, at least in my opinion, but not Totally ruled out.

jetech

If the previous owner told you it needs a tune that could be some of the issue you are having. You will have to fix the issues with the coolant temp sensor. You will also need to fix the P0200 dtc before a tune. The issue with the maf sensor is most likey coming from the pcm is seeing a different airflow than is "programmed" as normal for the factory camshaft. It will go away after the tune is done.