Gryz88

For the past couple months I've been occasionally having to hit the gas pedal to get the engine to start.

The last week or so it seems like I have to do it every time.

Any ideas on what could cause this? (plugs and wires were changed less than a year ago, and I put a bit of injector cleaner in the engine last fill-up, no difference)

rodj

Opening the throttle over a certain % while cranking causes the ECM to shut off the injectors because it thinks you are trying to clear a flooded engine;
which you may have if your injectors are leaking fuel into the intake.

How old are your injectors?

Gryz88

Couldn't tell you bought the car 3 years ago, its been primarily just a summer car since...minimal use.

I did do a voltage check across the injectors about a year and a half ago. You think I should check again?

Paul Workman

A place to start...

I'd want to eliminate the Throttle Position Sensor (TPS) as the culprit first. (Here's where a scanner comes in handy.) Look it up in the FSM, but in any case, the voltage should change smoothly across the full range of throttle position. If it becomes erratic, or disappears at or near the IDLE position, the sensor might need to be replaced, if it hasn't slipped position somehow.

If that doesn't turn up anything, then a full scan can really cut to the chase, instead of trying this and that etc, etc, etc. (AutoZone will do the scan for you - free)

A fuel pressure leak down test would shed some light on a leaking injector(s) as well. Having the LT5, I get spoiled, but reading the plugs next might be in order as you progress...

P.

Gryz88

I actually have a separate issue that points at the TPS, I guarantee you that's it!

I'll pick one up from O'Reily's tomarrow.

Thanks guys. I'll post an update.

Gryz88

That solved the problem!

Thanks.

88BigGuy

What was the other issue? I have the same problem as you and my injectors are less than 5 years old.

aklim

I suspect that it is the dirty TB and IAC passages. Get them cleaned first and then check the engine for leaks

You really didn't think that the snake oil can do that much, did you? Check fuel pressure and see if it leaks off quickly after shutdown. Take the injectors out and have them sent to FIC for testing and cleaning. I'm sure that by now it is either crapped out or dirty. Multecs were never the best injectors by far.

Any mods?

aklim

You mean ohm check, don't you? Either way it only tells you that the coil has the correct ohm reading or not. Send it out and have it tested and you can see if there is obstruction in the injector and what the flow rate and spray pattern is. Cleaner in a can doesn't tell do that for you. I have never ohmed any injector I owned. I just send it out every so often, say 3 yrs for cleaning and testing and not bothered with the snake oils.

aklim

Thought. I thought it has to be at WOT or almost WOT for that?

JackDidley

Does an 88 have a cold start injector ? When my car was starting funny, the CSI was not working. Tuned it out of the chip and dont have it now.

Amethyst643

Wow. This sounds like exactly what mine was doing.

This must be a common problem. No wonder you are a pro at diagnosing it!

For me, it was the IAC. Btw, it still runs great!

aklim

Wouldn't have anything to do with the fact that mine was caked up and I was chasing everything under the sun.

Glad it worked out. Hope it keeps working out. I'd still get that scanner for the next time something else goes wrong

Gryz88

The issue was general idle throttle quality.

Gryz88

I cleaned out the TB and IAC passages when i replaced the TPS sensor, I figured why not I was already there.

On the snake oil, I figured what can I lose other than the $2 that would have otherwise gone to a skoal tin. This may seem like a bit of a n00b question, but what is FIC?

Mods, not much other than Hedman Longtube Headers, Pypes 2.5" Exhaust, Smog/EGR/AIR Pump/Frisbee Disk Removed and other small misc.

Amethyst643

FIC = Fuel Injector Connection

http://www.corvetteinjectors.com/

aklim

So you cleaned all of that. Did you remove the IAC housing and clean that too? What is timing at? Did you check for leaks in the hoses either with brake cleaner sprayed at them or propane? If all that checks out, have you reset the idle? I would do it with a scanner and IAC counts.

Do you or does anyone know if you have a cold start injector? I'd spend the money there and on Skoal before dumping anything but fuel stabilizer in the tank for winter storage.

Gryz88

I just took the throttle body off the car, got new gaskets and spayed it all out with TB cleaner, scrubbed it down till it was shining. It was pretty dirty inside there. I removed the IAC from the throttle body and cleaned out the pathway but I didn't see a reason to "remove the housing" since I had replaced it last summer while working on that rough idle issue. So I know its relatively new.

You lost me here with the timing, no I did not check for hose leaks. Should I put that on the To-Do list? Which hoses in particular? The problem appears to be gone at the moment, but wouldn't be bad to know for the future.

aklim

If you replaced the housing last year, it should be relatively cleaned. I just worry that some of the crap you cleaned off might have washed down there. That is why I always take the housing off when cleaning. 6 or 7 torx bolts isn't that difficult to remove. The passages go thru the throttle body to the IAC so when washing the top, it could spray down. Not sure why people in general are so adverse to removing the housing but IMO, it is necessary when cleaning the TB.

I would make sure the timing is spot on. Then check for any hose leaks. On a car like this, it can crack and leak. Pretty much any hose can affect it all the way from the booster to fuel pressure hose to MAP (if you have one but I don't think so) to anything that has a connection to the intake. Yes, it works now but what does it mean that "it works now"? By that, do you mean it is all within spec or that you cannot detect anything amiss? Both can be and usually are different things. I couldn't detect that one injector was plugged from a collapsed basket since it wasn't that bad and the others weren't up to spec but the test showed all of that. The ECM has a way of compensating until it gets so far that it flashes a light or it just quits. Hook up a scanner and see what is going on. Take the TPS for instance. Just because you scanned it at the terminals doesn't mean the ECM is seeing it. The wire could be bad, for instance.