Bought a 2003 87k miles at auction site unseen

[konny]

Hello. So I bought this at auction a few days ago. It starts easy but dies almost immediately. It only stays running with my foot on the gas a little. But as soon as I take my foot off it has a rough file and dies. It seems to want to stay around 400rpms. I was hoping just a IAC valve. I slapped a new one on but it didn't help any. These are the codes it has now. Also. The replacement iac from auto zone doesn't look exactly the same but still plugs in.

 

[konny]

Also. The iac valve that was on the vehicle has a vent cap and looks to be for a 5.4. My replacement I put on does not have a cap but is definitely for a 3093 4.6. Would this be a problem?

 

[Hamfisted]

What do the sparkplugs look like ? Clean the MAF . Is there an air filter ? Not K&N I hope. Look for vacuum leaks or smoke test the intake system with a smoke machine. Rotted vacuum lines are common at that age. Cylinders 7 & 8 are the two rear cylinders on the driver's side for those misfires. Pay close attention to their sparkplug & coil condition. Any service records with it ? I hope you didn't pay much for it.







.

 

[konny]

What do the sparkplugs look like ? Clean the MAF . Is there an air filter ? Not K&N I hope. Look for vacuum leaks or smoke test the intake system with a smoke machine. Rotted vacuum lines are common at that age. Cylinders 7 & 8 are the two rear cylinders on the driver's side for those misfires. Pay close attention to their sparkplug & coil condition. Any service records with it ? I hope you didn't pay much for it.

.

Thank you. No I didn't pay much. If it's too much work I'll just put it back in auction. Either make a few or lose a few. Thanks for all the tips. I can't check out till Tuesday. Do you know if there is a way to raise the idle rpm just so I can drive it home the 50 miles?

 

[Hamfisted]

There's a set screw there on the throttle body, the side with the cable on it. You can turn that in to raise the idle. But if you ever get it running right you'll need to turn that back down so the IAC can manage the idle speed.









.

 

[konny]

You're amazing.

 

[AftonJay]

With those misfire codes i would start with plugs and depending on how the ones in those two cylinders look, maybe a couple coils.

 

[konny]

Hello. Did I maybe just figure out a piece of the puzzle. I started researching about how to do a Smoke Test. I saw a vid where it said to go in by the brake booster. I never knew a car had such a thing. lol. Anyways. The other big problem with my car is the brakes are super duper spongy soft to the point of not braking right. Like when I push the pedal it makes a noise like air escaping. Then I read brake booster is a vacuum. Could my leak be there.m? Thanks.

 

[whtbronco]

Yes it's entirely possible you have a vacuum leak inside the brake booster. It has a rubber diaphragm inside and can dry rot and crack over time. You can disconnect the brake booster vacuum hose and plug the hose with something that cannot get sucked in, like a bolt or rubber cap that fits snug over the hose. Then start the engine and see if it stays running at idle. That will isolate the booster at least. Do not try to drive without the booster, you will have very little brakes. Often times the failure is just the hose fitting grommet though.

You mentioned the brake are spongy, that can be from multiple issues including bad brake fluid, it should be almost perfectly clear. When it gets dark it's a sign it has absorbed moisture. Moisture compresses, brake fluid does not. You may also have air in the brake lines and calipers. Flushing the brake fluid is low cost and pretty easy to do with 2 people and will eliminate air and bad brake fluid. It will also give you an opportunity to inspect the brake lines and hoses for any leaks.

BTW, the engine is the vacuum source, the brake booster is vacuum operated, but has no ability to produce vacuum.

 

[konny]

Thank you so much. So I just drove it 55 miles. I did it with the MAF unplugged so it would stay running at idle. Probably was a bad idea but it's home now. Here is what I learned on the journey. 1. As soon as the car is moving forward it runs like a dream. Smooth, no weird sounds or smells, can't feel any misfires. Now the brakes. The brake feels like it is easy to push for a small bit of pedal travel then the brakes start working ok but to get to a dead stop you need to put a ton of pressure on the pedal. Which again has me thinking Booster. So I'll start there and thank you for the test you recommended , I'll start there. But here is the only other thing I learned on my drive and maybe it's completely unrelated. When I'm at idle or going slow the a/c almost completely stops. By that I mean the force of the airflow drops down I'd say by 80% and I'm not sure but maybe it doesn't blow cold. Now when I get on the accelerator and start driving, after about 1min or so, it regains all its power and is icy cold. Thanks again