HOT START issue g3.

[Army74D]

Before I get flamed on, let me make one thing clear; I did search google. In fact, spent hours reading through different websites/ forums/ threads. I'm no expert nor a noob.


Car: 1999 Acura Integra GS (stock b18b1-obd2).
Problem: HOT START issue.

It's been talked about over and over again but this time is different than I have experienced, or that I can find online anywhere.
The problem is a hard start on HOT start (Normal operating temperature).
The car either a.) cranks over and starts up but will bog erratically and nearly stall unless I give it some gas. or b.) crank but not start at all.

Things I have checked and/or replaced and I know are good.
1. Main Relay.
2. Distributor.
3. Spark Plugs.
4. Spark Plug Wires.
5. Timing.
6. Fan Switch Jumped.
7. Fuel Filter.
8. Fuel Pump.
9. Compression.
10. No Vacuum or Exhaust leaks.
**Motor was completely rebuilt less than 1500 miles ago.


Can fuel injectors be a culprit?

Any other suggestions?

Need help asap!

 

[Army74D]

Need to add, I have NO check engine light/codes.

 

[Muckman]

Before I get flamed on, let me make one thing clear; I did search google. In fact, spent hours reading through different websites/ forums/ threads.

I have no doubt that you did your homework on this issue considering how well written this thread is.

Now that being said I can tell you the injectors are the culprit. When the engine is at full operating temp then shut off the injectors heat soak without cool fuel running through them. As heat increases, resistence increases. Now during hot start, cranking fuel doesn't compensate for this and each injector ms pulse equals less fuel injection.

There is nothing really that can be done on a stock ECU. It's an issue with older style injectors. New modern style injectors aren't as sensitive to temperature. To prove this theory try leaving your hood open when you're parked before a hot start. Or buy a can of compressed air and spray the injectors to cool them before a hot start.

When I tune cars I use the ECT fuel trim to increase cranking fuel values. Coolant temp is indirectly related to injector temp but it allows me to defecto correct this hot start issue by piggy backing off a high coolant temp condition which usually parallels.

 

[Army74D]

I have no doubt that you did your homework on this issue considering how well written this thread is.

Now that being said I can tell you the injectors are the culprit. When the engine is at full operating temp then shut off the injectors heat soak without cool fuel running through them. As heat increases, resistence increases. Now during hot start, cranking fuel doesn't compensate for this and each injector ms pulse equals less fuel injection.

There is nothing really that can be done on a stock ECU. It's an issue with older style injectors. New modern style injectors aren't as sensitive to temperature. To prove this theory try leaving your hood open when you're parked before a hot start. Or buy a can of compressed air and spray the injectors to cool them before a hot start.

When I tune cars I use the ECT fuel trim to increase cranking fuel values. Coolant temp is indirectly related to injector temp but it allows me to defecto correct this hot start issue by piggy backing off a high coolant temp condition which usually parallels.

Wow, you're f***ing awesome! Thanks for the great info man!

What would you recommend on me doing?
I got some used oem injectors sitting around I can use as temporary replacements until I can afford newer, better replacements. But how can I know for sure which injector(s) to replace?
I did the screwdriver test to listen for the tapping/clicking noise and it sounded normal on all four even at normal operating temp. This is currently my daily driver and need to get around without having to worry about being stranded for hours at a time.

 

[Muckman]

Start by testing the theory that this is in fact caused by the injector temperature. Best is to use an infrared thermometer to take the temp of the injector when its doing this. See if it correlates with the issue. Easiest way to test is to simply try cooling them down - as I said try leaving the hood open between stops or spray them down with compressed air.

Replacing the injector with another stock injectors wont fix the problem. Its a fundamental issue. If you were OBD1 Id say you could easily upgrade to a modern Bosch EV14 injector that doesn't suffer from this problem but being in CA, you can't do that. (unless you want to swap it back for inspection)

 

[TheIVJackal]

Interesting idea on the injectors. Could it also be an issue with the IACV not letting in enough air during start? Seems to me it would be the same symptoms.
- Aaron

 

[Muckman]

Well you could test that theory by tipping in the throttle which lets air in the same. Throttle tip in can also be used to thin out cranking fuel if its too much. Unfortunately for the hot start condition you need more fuel.

 

[Nick_C78]

I second that compressed air canister trick. Just get one of those keyboard duster cans and test it. Should cool faster than popping your hood. How consistent is your issue? Is it after every hot start?

 

[NemesisCBR]

Assuming the spare injector is not aged, wouldnt that be the typical solution? The problem as described lays within aging material in the injector isnt it?

 

[Army74D]

I second that compressed air canister trick. Just get one of those keyboard duster cans and test it. Should cool faster than popping your hood. How consistent is your issue? Is it after every hot start?

Yes.. Every hot start. Today was the first time te car actually died out on me which tells me he problem is getting worse.

 

[Nick_C78]

The fact that it happens every time is actually a good thing when it comes to diagnosing. It means that it will be easy to test. Start with Muckmans tips and go from there. Like I said the compressed can trick will be the fastest way to test it.

 

[Army74D]

The fact that it happens every time is actually a good thing when it comes to diagnosing. It means that it will be easy to test. Start with Muckmans tips and go from there. Like I said the compressed can trick will be the fastest way to test it.

Thanks man, and thanks to everyone else. Most "hot start" threads I found online ended with everyone pointing to the main relay being the problem. I know for a fact it's not my main relay.


Will cleaning the injectors help or are they usually just done for and need to be replaced?
I read somewhere online that something called "chemtool" was used by letting the injectors sit and soak in it.

 

[Army74D]

Start by testing the theory that this is in fact caused by the injector temperature. Best is to use an infrared thermometer to take the temp of the injector when its doing this. See if it correlates with the issue. Easiest way to test is to simply try cooling them down - as I said try leaving the hood open between stops or spray them down with compressed air.

Replacing the injector with another stock injectors wont fix the problem. Its a fundamental issue. If you were OBD1 Id say you could easily upgrade to a modern Bosch EV14 injector that doesn't suffer from this problem but being in CA, you can't do that. (unless you want to swap it back for inspection)

Thanks man, I'm going to try the compressed air test today after work. I'll keep this updated.

 

[Army74D]

Start by testing the theory that this is in fact caused by the injector temperature. Best is to use an infrared thermometer to take the temp of the injector when its doing this. See if it correlates with the issue. Easiest way to test is to simply try cooling them down - as I said try leaving the hood open between stops or spray them down with compressed air.

Replacing the injector with another stock injectors wont fix the problem. Its a fundamental issue. If you were OBD1 Id say you could easily upgrade to a modern Bosch EV14 injector that doesn't suffer from this problem but being in CA, you can't do that. (unless you want to swap it back for inspection)

Interesting idea on the injectors. Could it also be an issue with the IACV not letting in enough air during start? Seems to me it would be the same symptoms.
- Aaron

The IACV was cleaned out.

 

[Muckman]

You've eliminated virtually every other possible cause but try to confirm the injectors are the culprits before swapping them out or cleaning.

You aren't going to be able to effectively clean an injector without running the solution through the injector. You need them professionally cleaned, which should cost $40-50 for 4. Just try the spare injectors if you already have them but I doubt they will be any better. I've seen this hot start problem with new RC injectors. That old fat style injector is called an EV1, they have been around since 1976. They stink.