rough runner/slow idle

This site may earn a commission from merchant affiliate
links, including eBay, Amazon, Skimlinks, and others.

Feb 28, 2006
I have a 93 cruiser that has had a problem with a low idle (200-400rpm) that has slowly progressively over time gotten worse. At speed, it ran smooth otherwise. Since the problem progressively worsened, and at times would cut out, I took it in to my mechanic who thought it was a mass air flow meter, I replaced it with a salvage one, since they are $750 vs $100, and it really didn't help much other than it doesn't cut out. It still has a low idle and runs a bit rougher up to 1600rpm. I then took to the nearest toyota certified mechanic, who thought it is the IAC and intake hose and he wants $600 to replace.

Here is my deal, I came in looking at similar problems that others have had, and it looks to me to be either a wiring harness issue around the EGR vs. the throttle body needing cleaned and tuned and hoses replaced.

What do you all think and do you experts out there have any other recommendations, like would you spend the $600 on the IAC/hose??

Thanks a mil in advance
First thing to check is the intake hose. It is probably cracked and sucking air between the MAF and the TB
A cracked intake hose isn't at all unusual and could easily cause the symptoms you describe. I cant recall the cost of one new (Dan?), but I believe it was somewhat pricey. Some have had results repairing these and a quick search should offer some insight as to the procedure. Good luck and keep us posted.


Oh, BTW, :flipoff2: Welcome!
I changed the intake hose, and it did help quite a bit, it doesn't have as dramatic low idle bump and rise (200-->450rpm), it is smoother, but now, when first taking off and only when first taking off for the first mile or so it is stone cold 'cold' acting, as in when I give it a bit of gas it acts like it would like to stall, runs flat...sputters a bit at times. Later, it smooths out, idles back much much better. I have driven it about a half dozen times.

I did clean the IAC, it seems to be clean and actuated fine.
The toyota dealer said he cleaned the TB, but did so while I was waiting and was less than an hour?

Any thoughts? Plugs and wires??
thanks ahead of time!!
Plugs and wires would be a good start. I assume you checked the hose for cracks before replacing it? how many miles on your truck and are you running the original ignition components?

If your Check engine light comes on at startup, but is not giving you a code, the chances are that it is something maintenance related rather than a sever defect.

I would inspect all of your ignition components first, and also spray water on your wires at night and look for sparks.

Do a search on the Bubble test to make sure your HG is fine.

The only other thing that I can think of the check is the MAF, just be careful with it.

Good Luck,


Edit: Some have had good luck with redline or seafoam treatments to smooth their engines out as well
its a fairly low milage, 130k, all original.

The air intake hose did have a leak in it, and as mentioned, it improved. I will replace plugs and wires and run Redline through it.

Thats a good idea on the spark from a short.

Let me ask a stupid question, where is the EGR located on these, since that seems to be a problem area?? Is it behind the TB, close to the firewall??

If the battery or ECU fuse was unplugged while the work was done, it will take the ECU time to relearn the idle. 3-5 trips usually.
Let me ask a stupid question, where is the EGR located on these, since that seems to be a problem area?? Is it behind the TB, close to the firewall??



If you haven't seen natergator's setup for downloading the FSM, it should be on the first five pages of this forum. cost is ten bucks and about an hour total, and it will be invaluable for working on your rig.
the Cruiser runs much much smoother now.

I replaced all the plugs and wires and ran some seafoam directly through the TB as instructed and it ran 100% better.

After warm up it runs perfect without a hitch.

Start up and cool running however there is a very subtle stumble hesitation, but I think I will run more seafoam through and give it a bit of time.

Hi fella's,
here is an update on what's going on with my rough idle situation. I virtually only happens now when I warm up, and immediately upon starting revs up to about 1600+ for a few seconds, falls down to literally 100-200rpm and barely pulls idle, up and down up and down, as i usually just blip the throttle and it responds and settles around 600rpm.
-I replaced the intake hose
- replaced the plugs and wires
-cleaned the throttle body w/seafoam treatment, and yes, it blew smoke like you wouldn't freakin believe...shameful
-replaced EGR modulator

This was all due maintainance and needed, and the IAC still is in the back of my head, but lookin at this little deal and thinking the factory wants $425 for this guy is hard for me to swallow. Have you guys ever lubed it and cleaned it w/success or should I look elsewhere for my rough idle???

thanks for any help out there

Users who are viewing this thread

Top Bottom