Cold start problem

[darwin-t]

My grandson has an '89 Reatta. It dies repeatedly when first started, especially when put into gear. It runs very rough at first.

 

If I just let it run for about 3 minutes, it runs fine. I don't think it sounds like a crankshaft or camshaft position sensor.

 

I have cleaned the MAF sensor.

 

I suspect the idle control sensor, but can't identify it. I tried to remove the throttle body to get to things not easily removed but am unable to pull it off. There is a steel tube that comes from the passenger side and makes a 180 degree bend and this keeps the throttle body from coming loose. I can't see where that pipe goes.

 

Any advice would be greatly appreciated

[2seater]

Is the check engine light on? Idle air control is on the rear of the throttle body. The actuator faces to the drivers side, two non-magnetic stainless screws hold it in. Remove and clean the inside passageway and pintle on the electric actuator. Those steel pipes, two of them, are for coolant flow to warm the throttle body and prevent icing. Do not disturb them unless you have new gaskets and seal.

If that doesn't help, unplug the MAF and see if the cold start issue gets better. Do you know how to access onboard diagnostics?

[darwin-t]

2 hours ago, 2seater said:

Is the check engine light on? Idle air control is on the rear of the throttle body. The actuator faces to the drivers side, two non-magnetic stainless screws hold it in. Remove and clean the inside passageway and pintle on the electric actuator. Those steel pipes, two of them, are for coolant flow to warm the throttle body and prevent icing. Do not disturb them unless you have new gaskets and seal.

If that doesn't help, unplug the MAF and see if the cold start issue gets better. Do you know how to access onboard diagnostics?

Thank you very much.

 

E041    B671 (Cruise control)    C553

 

I think I saw the actuator. Is it under the throttle body and point toward the left fender? I got one screw out and the phillips screwdriver is slipping in the other. I didn't want to round it off. That is why I was trying to remove the entire throttle body.

 

Edit. I unplugged the MAF and it seemed to have helped. What does that mean? Surely I can't just leave it unplugged.

I'm not sure if it was completely cold. I drove it around the block about 6 hours ago. I'll try again in the morning.

Edited September 13 by darwin-t (see edit history)

[2seater]

The item in your photo is the IAC. A set of JIS, Japanese Industrial Standard, screwdrivers work better in those blasted screws. Another option is one of those hammer blow type drivers. The impact and twist, within reason, sometimes will help. Code 041 for the cam sensor may or may not cause rougher than normal idle and low speed depending on how close the injector timing is every time you start it. It shouldn't stall the engine, at least not by itself, but may magnify something else that is also amiss. You can operate with the MAF disconnected but it is only to help narrow the focus if there is a problem. If yours is only misbehaving when cold, it will be more difficult to find if it goes away when warmed slightly.

[rogold99]

Might want to check the coolant temp sensor and the manifold intake air temp sensor readings too.

 

Edited September 14 by rogold99 (see edit history)

[EmTee]

11 hours ago, rogold99 said:

Might want to check the coolant temp sensor

Yes - I had a Chevy C1500 that had a similar issue at cold startup, but ran perfectly once warm.  It turned-out that sometime prior it must have overheated and sprayed coolant onto the top of the engine.  When I unplugged the coolant temperature sensor I found rust stains on the plug and the connector cavity of the sensor was full of rusty residue.  I cleaned the plug and replaced the sensor and the problem was solved.  There was no code, as nothing was out-of-range, the sensor was simply telling the ECM that the engine was always warm.

[darwin-t]

On 9/14/2024 at 9:04 AM, EmTee said:

Yes - I had a Chevy C1500 that had a similar issue at cold startup, but ran perfectly once warm.  It turned-out that sometime prior it must have overheated and sprayed coolant onto the top of the engine.  When I unplugged the coolant temperature sensor I found rust stains on the plug and the connector cavity of the sensor was full of rusty residue.  I cleaned the plug and replaced the sensor and the problem was solved.  There was no code, as nothing was out-of-range, the sensor was simply telling the ECM that the engine was always warm.

Does the C1500 have the same engine? I couldn't find the temperature sensor which is sad considering my first car was a 1947 Dodge. I should be able to find it easily

 

There is a little coolant on top of the block under the intake manifold.

 

I replaced the idle air control sensor, cleaning out the port. I also replaced the cam position sensor. 

 

it seems to be fixed. I will let it sit overnight and take it for a test drive in the morning

[EmTee]

10 hours ago, darwin-t said:

There is a little coolant on top of the block under the intake manifold.

Look carefully around the intake manifold.  Coolant might mean there's an intake manifold gasket leak at the head.  The rough running at startup could be due to coolant that has leaked into the cylinder after shutdown being burned-off at startup.  Check the dipstick - is there any evidence of coolant in the oil?  Can you post a picture of the coolant leak?

[darwin-t]

4 hours ago, EmTee said:

Look carefully around the intake manifold.  Coolant might mean there's an intake manifold gasket leak at the head.  The rough running at startup could be due to coolant that has leaked into the cylinder after shutdown being burned-off at startup.  Check the dipstick - is there any evidence of coolant in the oil?  Can you post a picture of the coolant leak?

Replacing the idle air control valve and camshaft position sensor did not help

 

Here is the coolant leak. Taken from the front of the car.

 

I thought I found the coolant temperature sensor on the top of the block behind the power steering pump, but it has 3 wires and evidently they only have two

 

[2seater]

That puddle at least gives us an idea that it is in the front,  unless it is at the rear as well? Aside from the intake manifold possibly leaking, there is also the thermostat although they have a pretty good record of staying dry. It would be best if you can sop up the liquid as much as possible to see if you can better localize the leak. That said, intake manifold coolant leaks are not uncommon and are usually from galvanic corrosion of the intake manifold.

 

The coolant temperature sensor is below and slightly to the rear of the throttle body. It points toward the drivers fender or may be angled to the rear, but it is in that general location, and is threaded into the intake manifold.

[darwin-t]

I have eliminated a lot of stuff. I cleaned the MAF, replaced the camshaft position sensor, idle air control valve, and coolant temperature sensor. I cleaned the throttle body.

 

It started okay, seemed to be idling better. It did not immediately die when I put it in gear, but it wouldn't really move the car. I let it warm up for a couple of minutes and it ran smoothly except when when I pressed down the gas pedal from idle. It would hesitate, not do anything and then accelerate quickly.

 

I will let it sit overnight and try again tomorrow. 

 

Would a vacuum leak does this? I will test for those by spraying carb cleaner around or maybe a propane torch. That would certainly be less messy.

 

But I fear it in the manifold gasket or a head gasket.

 

I cleaned up the leaked coolant. I didn't see any leakage in the 5 or so minutes I had it running. The coolant is only at the left side of the engine - toward the front of the car.

 

I read the codes on it.
E034 History

 

B671

E041

 

No coolant in the oil

 

Edited September 17 by darwin-t (see edit history)

[EmTee]

I'd feel better about the cooling system if you could do a pressure-test on it.  I would also suggest starting with a compression test.

[2seater]

What is your TPS reading at idle and does it increase smoothly with throttle input? Engine doesn’t need to be running to check.

 

What is your actual fuel pressure, key on engine off, and when running at idle. Second part; does pressure increase as you blip the throttle?

[darwin-t]

11 hours ago, 2seater said:

What is your TPS reading at idle and does it increase smoothly with throttle input? Engine doesn’t need to be running to check.

 

What is your actual fuel pressure, key on engine off, and when running at idle. Second part; does pressure increase as you blip the throttle?

TPS is 0.78 at idle, increases smoothly to 3.20 at full throttle

Air flow is 0.0 without engine running, 7.5 at idle, 16.5 when engine speed is increased.

IAC 26-48

MS INJ PM 18.8 when engine isn't running. 4.2 at idle, is increases when I press accelerator. 

 

When I started it, the idle was high at first - that never happened before. IT ran for a couple of minutes while I got the readings. It ran perfectly when I drove it.

 

I'll let the engine cool off and try again and try to drive away right after I start it.

 

I will also do compression test.

Edited Tuesday at 01:10 PM by darwin-t (see edit history)

[EmTee]

30 minutes ago, darwin-t said:

When I started it, the idle was high at first - that never happened before. IT ran for a couple of minutes while I got the readings. It ran perfectly when I drove it.

 

Maybe a sticky (or dirty) EGR valve?

[darwin-t]

2 hours ago, EmTee said:

 

Maybe a sticky (or dirty) EGR valve?

I replaced it and cleaned the port.

 

[2seater]

The tps voltage is well out of specification. It should be .38-.42 volts at closed throttle and well over 4.0 volts at full throttle. A high tps at closed throttle can cause a high idle. I suspect the tps needs to be replaced and adjusted properly. The tps acts a bit like the accelerator pump on a carburetor. It doesn’t inject fuel but it tells the ECM what the throttle is doing instantly 

[darwin-t]

This thing is driving me batty. Not it won't start and stay running. It misfired VERY badly, then backfires and stops.

[Ronnie]

1 hour ago, darwin-t said:

This thing is driving me batty. Not it won't start and stay running. It misfired VERY badly, then backfires and stops.

Look on the bright side. It's much easier to troubleshoot the problem when an engine won't run.

[DAVES89]

Check the crank sensor to see if it's out of adjustment. Or better yet just replace it.

[2seater]

I agree with the above. When you start to get problems that seem to dance around from one area to another, and don't set a code, you need to look at the absolutely most important item and that is ignition. Nothing else matters. If you verify spark, try a spray of starting fluid into the intake to see if it will fire

[darwin-t]

On 9/17/2024 at 2:10 PM, 2seater said:

The tps voltage is well out of specification. It should be .38-.42 volts at closed throttle and well over 4.0 volts at full throttle. A high tps at closed throttle can cause a high idle. I suspect the tps needs to be replaced and adjusted properly. The tps acts a bit like the accelerator pump on a carburetor. It doesn’t inject fuel but it tells the ECM what the throttle is doing instantly 

I see the TPS, but can't get a screwdriver on it straight. How does one remove the throttle body? I see two nuts. I had removed them earlier and the throttle body was still secure.

[2seater]

Yes, the TPS location is rather difficult, and the screws are non magnetic like the others. Always place a rag or something else underneath to keep them from disappearing. I use a dual ended bent screwdriver or a tiny ratchet designed to hold 1/4 hex screwdriver tips.

 

The coolant tubes on the underside of the throttle both insert into the lower part of the throttle body and seal via O-rings. The outer one, which is visible, is bolted to the intake manifold base. That must be unbolted and loosened from the manifold face and then the T/B should pull off the hidden tube with a pull and twist if everything goes well. Thirty odd years of possible rust/corrosion may resist a bit.

 

 I would verify spark and fuel before taking this apart.

Edited Thursday at 04:28 PM by 2seater (see edit history)

[darwin-t]

7 hours ago, 2seater said:

Yes, the TPS location is rather difficult, and the screws are non magnetic like the others. Always place a rag or something else underneath to keep them from disappearing. I use a dual ended bent screwdriver or a tiny ratchet designed to hold 1/4 hex screwdriver tips.

 

The coolant tubes on the underside of the throttle both insert into the lower part of the throttle body and seal via O-rings. The outer one, which is visible, is bolted to the intake manifold base. That must be unbolted and loosened from the manifold face and then the T/B should pull off the hidden tube with a pull and twist if everything goes well. Thirty odd years of possible rust/corrosion may resist a bit.

 

 I would verify spark and fuel before taking this apart.

Thank you. It runs perfectly after warming up for a couple of minutes. The only problem is when it is first started when the engine is cold

 

[darwin-t]

On 9/19/2024 at 12:27 PM, 2seater said:

Yes, the TPS location is rather difficult, and the screws are non magnetic like the others. Always place a rag or something else underneath to keep them from disappearing. I use a dual ended bent screwdriver or a tiny ratchet designed to hold 1/4 hex screwdriver tips.

 

The coolant tubes on the underside of the throttle both insert into the lower part of the throttle body and seal via O-rings. The outer one, which is visible, is bolted to the intake manifold base. That must be unbolted and loosened from the manifold face and then the T/B should pull off the hidden tube with a pull and twist if everything goes well. Thirty odd years of possible rust/corrosion may resist a bit.

 

 I would verify spark and fuel before taking this apart.

I got it off and will be using allen bolts when I put it back on.

The one I bought doesn't fit so I tested my old one.

On one side, the resistance goes from 767 - 5940 (5.94k)

On the other side, it goes from 5730 (5.73k) - 993

Is it any good or do I need to replace it?

How do I adjust it?

 

Thank you very much

 

Also, while researching this problem, I ran across camshaft magnets falling out/apart. I am still getting an E041 code. Do I need to look at the magnet?

 

Edited Friday at 04:57 PM by darwin-t (see edit history)

[2seater]

I don't understand the resistance readings for a tps. It is normally installed and the reading in diagnostics is in volts. The input from the ECM is nominally 5.0vdc and the TPS is a potentiometer.  If you look at the TPS, the mounting holes are slotted so it can be rotated in place for adjustment.

 

The cam sensor code is most often the missing magnet. You need to remove the sensor and rotate the engine by hand until the magnet holder is visible in the hole.

[darwin-t]

6 minutes ago, 2seater said:

I don't understand the resistance readings for a tps. It is normally installed and the reading in diagnostics is in volts. The input from the ECM is nominally 5.0vdc and the TPS is a potentiometer.  If you look at the TPS, the mounting holes are slotted so it can be rotated in place for adjustment.

 

The cam sensor code is most often the missing magnet. You need to remove the sensor and rotate the engine by hand until the magnet holder is visible in the hole.

I took it off and tested it with an ohm meter. 

This was whet I got when it was installed

TPS is 0.78 at idle, increases smoothly to 3.20 at full throttle

[2seater]

2 minutes ago, darwin-t said:

I took it off and tested it with an ohm meter. 

This was whet I got when it was installed

TPS is 0.78 at idle, increases smoothly to 3.20 at full throttle

I figured that was the reading from a VOM, and voltage probably could be calculated, but not how it is normally done. I saw the previous reading and that is well outside the normal range. Is it possible something is limiting throttle travel? A little odd to be high voltage on the bottom and low voltage at the top.

[darwin-t]

I originally asked about the magnet, but now I have removed the old one and installed a new one. Now I wait for 24 hours. I tested the old one with a screwdriver and didn't detect any magnetism

 

I put the throttle position sensor back in, adjusted it for 0.42 volts at idle. It didn't make any difference. 

If I set the voltage a little higher, would it speed up the idle? Not that I want to do that, just curious how it works.

 

 
 

 

Edited Saturday at 10:07 PM by darwin-t (see edit history)

[2seater]

If you replaced the magnet for the cam sensor, did the 041 code go away? The TPS idle value looks good, but what does the travel and maximum value look like?

 

A substantially high TPS at idle can cause an incorrect idle speed but it's primary function is to indicate the throttle position in real time. The MAF sensor tells the ECM what the actual airflow is entering the engine as a result of the throttle opening, sort of a cause and effect.

[darwin-t]

51 minutes ago, 2seater said:

If you replaced the magnet for the cam sensor, did the 041 code go away? The TPS idle value looks good, but what does the travel and maximum value look like?

 

A substantially high TPS at idle can cause an incorrect idle speed but it's primary function is to indicate the throttle position in real time. The MAF sensor tells the ECM what the actual airflow is entering the engine as a result of the throttle opening, sort of a cause and effect.

Thank you. I am letting the JB Weld harden, I'll be able to try it tomorrow afternoon.

Cleaning the MAF sensor stopped that code.

TPS shows 0.42 at idle and 4.10 with the gas pedal floored

I cleared the codes this afternoon.

With all of the (probably unneeded parts) I've put on it, it should run fine now. I've had this car in my garage for weeks and he is driving my car. I want my Century back.