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Ted Ritter
Ted Ritter, Toyota Master Tech
Category: Toyota
Satisfied Customers: 4335
Experience:  Toyota Master Tech, ASE Certified
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1998 Toyota Camry LE 4 cyl 130k Miles When we got it ran ok

Customer Question

1998 Toyota Camry LE 4 cyl
130k Miles
When we got it ran ok at high rpm but rough at idle, didn't stall though.
Started stalling when foot taken off gas sometimes.
Got a code for EGR, modulator was bad, replaced, no more code.
Still runs bad and stalls. Like the ignition momentarily drops out then comes back. You can hold it at say 2500 and watch the tach drop a couple hundred for a second then catch back up. It's consistant but random. Might do it again in 5 sec, 10 sec, or 30 sec. When it does it at low rpm it kills the motor. My son refuses to drive it now because it died on him at a busy traffic light, lol. Changed plugs, no help. IACV shaft is loose and moves freely. Don't know where to go next.
Submitted: 1 year ago.
Category: Toyota
Expert:  Ted Ritter replied 1 year ago.

Hello, thanks for posting

You mentioned replacing the EGR modulator valve, what was the code number before replacing the valve?

Is the check engine light on now and are there any codes at this time?

Customer: replied 1 year ago.
P0401. I tested it by blowing air through it and it only came out one hole. On the new one air came out of both holes. After changing it the code cleared and has not come back, even though it still runs bad as described. Drove yesterday like 5 miles, no light.
Expert:  Ted Ritter replied 1 year ago.
Thanks for the reply
The modulator won't cause the problem, does it consistently idle rough or is it intermittent? Does the engine have a distributor or two coils at the end of the cylinder head?
Customer: replied 1 year ago.
Not just rough at idle, it does it even if I hold it at a higher rpm like 2000 or 2500. It's almost like the ignition dies for a half second then comes back on. Just picture tachometer sitting at 2000, dropping to immediately 1800 then climbing back to 2000, then happening again in a few seconds, or maybe as much as a minute later. It happens when in park and just revving up, but it's worse when under load. The engine can die completely if this happens at idle, cause it doesn't have time to recover. No distributor, yes two coil.
Expert:  Ted Ritter replied 1 year ago.
How long have you owned this car and how did this start?
Has anything been replaced recently other than the egr modulator?
Have the spark plug wires been checked or replaced, check the connectors in the tubes, make sure they are not cracked or leaking high voltage.
Customer: replied 1 year ago.
We bought it about a year ago. It always had high vibration at idle but never died, and ran good at higher rpm. The check engine light has been on for a while but it still ran good. This particular problem just started a few days ago. I started by troubleshooting the P0401, which I think now was a separate problem not related to the rough running. I did change the spark plugs and fuel filter, no change. Haven't changed or checked the plug wires. Could a coil go intermittent like this? I don't see how it runs like this without producing any codes, I wish it would. I did have an 1133 with the 0401 when I first checked it but after clearing it has never come back.
Expert:  Ted Ritter replied 1 year ago.

I have to agree with you, there should be a check engine light and a misfire code, it does sound like an electrical issue though, the P1133 is for an air/fuel ratio sensor which is irrelevant to what you're describing, yes I suppose one of the coils could be the problem, before replacing them I would make sure the plug wire insulators are not cracked or leaking, this is common. Plug wires are fairly inexpensive so I would try those next and if necessary replace the coils.

Customer: replied 1 year ago.
I'll do the wires just for process of elimination. Would I be smart to buy one new coil and try it in both positions to see if any change? What's after that, ECM? There isn't any way to up the idle on that thing is there?
Expert:  Ted Ritter replied 1 year ago.

The ecm is usually the last thing to suspect, you can use one coil and switch it like you said, The idle is controlled by the idle air control valve but I'm not so sure that it's the problem due o the way the engine is running but it may be worth a try to clean the valve, it may be sticking. It's located at the bottom of the throttle body, it has to be removed to get the IAC valve off, the valve can be cleaned in most cases using a carbon remover/ air intake cleaner and a brush, clean the throttle body as well, the valve must move freely and close back by itself with a small gap remaining, if the valve is sticking it should be replaced.

Customer: replied 1 year ago.
I took the plastic piece off the IACV and rotated the shaft with my fingers and it's free and easy to rotate, seems to go about 1/4 turn.
Expert:  Ted Ritter replied 1 year ago.
Ok so it sounds like it is ok. Try the plug wires and the coils and let's go from there.
Customer: replied 1 year ago.
Ok I'll do that. I agree it seems electrical, but is there anything on the fuel side that I should check?
Expert:  Ted Ritter replied 1 year ago.

You've already replaced the filter, I guess there may be a slight chance of a fuel injector sticking.

Customer: replied 1 year ago.
Ok I'm back. I replaced both coils and no change in the problem. So at this point plugs, plug wires, and coils are new. I have created a video for you to show the problem. In the beginning of the video I zip tie a cheap ignition tester to the #1 plug wire. I would have expected the light to be very constant, but as you can see there are gaps where there is no spark, that doesn't appear to be normal to me. Later in the video I show you the tachometer (turn it up loud and you can hear the engine as well). I show it at idle and trying to hold it constant at a couple of different RPM's. You can see the tach just momentarily drops. It's very random. It still seems like a spark problem to me but the only thing left is the ECM. What do you think? You can access video on my Google Drive at :
Expert:  Ted Ritter replied 1 year ago.

Thanks for the video, that helps, the engine sounds a little noisy, kind of like a loose timing belt, do you know if the belt has been replaced, a worn ting belt can cause this, looking at the tach behavior , the fluctuation doesn't seem sharp enough to be electrical in my opinion, it's pretty easy to check the belt and how the timing marks line up by just removing the top part of the timing cover.

I'm going to be offline again today until later this after noon so if you could check the belt in the meantime it would be great,

Another thing to check, maybe before going to the belt is all the ground connections for the computer and injectors, there should be one at the rear of the intake chamber, they have a 10mm bolt with a few black brown wires, there are some at the rar of the head as well, check to make sure these ae tight, a quick way to check the computer ground is to check resistance at the E1 terminal in the check connector to ground, should be less than one ohm.

Customer: replied 1 year ago.
Not sure of the history on the timing belt. I'll make these checks tonight and get back to you tomorrow. You didn't make anything of the spark tester seeming erratic? The other thing I forgot to mention is still no codes from the computer, nothing since I changed that EGR modulator. It seems like it would pick something up, running this bad.
Expert:  Ted Ritter replied 1 year ago.

You know what I didn't see that part, let me check again.

Expert:  Ted Ritter replied 1 year ago.
Ok, got it, very odd, Does this have a separate igniter module mounted on the firewall, the thing is I hate to recommend replacing stuff if we don't have any codes, you should have an IGF malfunction code( spark confirmation)failure. Then again, a bad igniter would affect all cylinders the same. I'm kind of stumped right now, I'd like to rule out the belt as a possibility before replacing anything else but the ECM can't be ruled out at this time, you might want to check the connectors at the ecm for any corrosion or loose connectors, while there check all brown/black computer grounds.
Customer: replied 1 year ago.
I have a Haynes manual and it doesn't show a separate igniter on the 4 cyl, which this is. It show wiring straight from the ECM to the coils. The spark fluctuation appears on all the plug wires as well. I'll make all the tests you've mentioned. Can the ECM be tested by a dealership? Or would you recommend picking up a used one. It's $350+ new, too expensive just to buy and try.
Customer: replied 1 year ago.
There's an ECM on EBAY for $40. Would I need to worry about programming if it's the exact same make, model, and engine? If the other things you've mentioned show negative, do you think that would be worth a try?
Customer: replied 1 year ago.
I found one even cheaper on Amazon $18.00 free shipping. There appears to be a glut of these things out there. I definitely wouldn't mind risking that much, to rule it out. What do you think, any risks involved?
Expert:  Ted Ritter replied 1 year ago.
Of course there's a risk but for that price why not, just make sure the part numbers are the same, they start with 89661- then some more numbers these are important, got to leave for my appointment I'll get back to you later .
Customer: replied 1 year ago.
Ordered one from EBAY, $28.50 and the EXACT same numbers on it. Won't be here until Mon-Wed next week. I'll try to do those other checks between now and then. I'll let you know, lol.
Expert:  Ted Ritter replied 1 year ago.

Sounds good, eventually we'll figure this out.