1990 4x4 22RE - intermittent hesitation on acceleration
in [Toyota Trucks]
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From: dave.mcc on 2 Sep 2008 20:31 This truck will work properly for weeks - months. Then, for no apparent reason, it will lack power on acceleration. What's really interesting is that if I depress the accelerator all the way down, it will take off with all sorts of power AND if the rpm gets over 3000, it will also accelerate with lots of power. It's this "mid-range" acceleration that is suffering. I eventually wondered if the air flow meter was faulty although all the resistance measurements check out fine. I'm not sure what to look at next and the intermittent behaviour of the problem has me puzzled. Any ideas? Dave
From: al on 2 Sep 2008 22:02 On Sep 2, 8:31 pm, dave....(a)telus.net wrote: > This truck will work properly for weeks - months. Then, for no > apparent reason, it will lack power on acceleration. What's really > interesting is that if I depress the accelerator all the way down, it > will take off with all sorts of power AND if the rpm gets over 3000, > it will also accelerate with lots of power. It's this "mid-range" > acceleration that is suffering. > > I eventually wondered if the air flow meter was faulty although all > the resistance measurements check out fine. I'm not sure what to look > at next and the intermittent behaviour of the problem has me puzzled. > > Any ideas? > > Dave Check the EGR system. Disable the EGR by blocking the vacuum hose going to the EGR valve. If the problem disappears, you know it's an EGR problem. Good luck. Al
From: dave.mcc on 8 Sep 2008 13:01 On Sep 2, 7:02 pm, al <abuo...(a)msn.com> wrote: > > Check the EGR system. Disable the EGR by blocking the vacuum hose > going to the EGR valve. If the problem disappears, you know it's an > EGR problem. Good luck. Al When I tried this out, I discovered that the vacuum line to the EGR valve had been blocked off - it's been this way since I bought the truck some years ago because I've never checked it. Someone had inserted a small plastic plug in the hose. So, I guess the problem isn't an EGR problem??
From: dave.mcc on 8 Sep 2008 13:35 On Sep 8, 10:01 am, dave....(a)telus.net wrote: > On Sep 2, 7:02 pm, al <abuo...(a)msn.com> wrote: > > > > > Check the EGR system. Disable the EGR by blocking the vacuum hose > > going to the EGR valve. If the problem disappears, you know it's an > > EGR problem. Good luck. Al > > When I tried this out, I discovered that the vacuum line to the EGR > valve had been blocked off - it's been this way since I bought the > truck some years ago because I've never checked it. Someone had > inserted a small plastic plug in the hose. So, I guess the problem > isn't an EGR problem?? And, as a followup, I did the EGR valve test described in the shop manual - applied vacuum directly to the EGR valve - the truck immediately ran rough and nearly died. This is apparently what is supposed to happen. I took the truck for a test drive and the hesitation might have gone away, but it's done that in the past...which is what has made this problem hard to track down. Any other suggestions about what I could check out?
From: croy on 9 Sep 2008 00:03
On Mon, 8 Sep 2008 10:35:19 -0700 (PDT), dave.mcc(a)telus.net wrote: >On Sep 8, 10:01�am, dave....(a)telus.net wrote: >> On Sep 2, 7:02�pm, al <abuo...(a)msn.com> wrote: >> >> >> >> > Check the EGR system. �Disable the EGR by blocking the vacuum hose >> > going to the EGR valve. �If the problem disappears, you know it's an >> > EGR problem. �Good luck. �Al >> >> When I tried this out, I discovered that the vacuum line to the EGR >> valve had been blocked off - it's been this way since I bought the >> truck some years ago because I've never checked it. �Someone had >> inserted a small plastic plug in the hose. �So, I guess the problem >> isn't an EGR problem?? > >And, as a followup, I did the EGR valve test described in the shop >manual - applied vacuum directly to the EGR valve - the truck >immediately ran rough and nearly died. This is apparently what is >supposed to happen. I took the truck for a test drive and the >hesitation might have gone away, but it's done that in the >past...which is what has made this problem hard to track down. > >Any other suggestions about what I could check out? On my 1988 pickup with the 22R engine, there was another vacuum device (valve?) that had vacuum lines going to the EGR valve. It had a plastic cover that could be popped off for the purpose of cleaning the "filter elements" underneath. There was kind of a fuzzball, synthetic fiber blob (let me know if I'm being too technical here...), and another disk-like white-ish filter less than a mm thick. I carefully blew the dust out of the blob with a gentle blast from an air nozzle, and blew off the disk as best I could. The disk had one small area of heavy, black deposit on one side, right over a small port in the valve. When I reassembled it all, I rotated the disk so that the blackened spot was about 180 degrees away from the port. After reassembly, my old beast simply amazed me! Gone was the difficulty in starting, and the tendency to die right after starting. It's only been warm weather since doing this, but so far, also gone is the occaisional stumble on drive-away. And most surprising to me, the clutch chatter that had been plagueing this truck for a couple of years, has much subsided (I think because the torque on drive-away is smoother, and more muscular). And the first two full tanks of gas have produced mileage of just a hair over 25 MPG, up from an average of about 23.5. It sounds like you have the shop manual available. That's where I got the clue about this filter. Hope this helps. -- croy |