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Background:

I purchased my new-to-me '99 209000mi Rav4 a few weeks back as a 4wd commuter car for the snow/mud season in Kentucky, but also as an outlet for some DIY projects I'd like to try my hand in. Turning it into a spring and fall camping machine is the ultimate goal, as I have already turned my secondhand Kawasaki Versys 650 into an ideal summertime hammock camper. I need it to be reliable before I take it innawoods or invest the dough in an OME lift or fabricating a fold out trunk tent extension type situation. The car sat for who knows how long in the front driveway of an recently passed elderly lady's house. Son of the previous owner states it "Ran like a scalded cat" before they parked it, and he drove it to North Carolina a few months before his mother parked it. The woman who sold it to me informed me that she had financially helped her mother put in a new trans a year before she stopped driving it due to health issues and she was sure that the transmission was good. When I picked it up the battery was flat but not unresponsive so we jumped it and I drove it to the nearest gas station where I first ran into the warm hard start issue and the odd transmission behavior on the way there. We seafoamed the gas assuming that the hard start and transmission behavior was from stale gas and a dried seal leaking some fluid out. I could tell from the sketchy drive up I-75 that it needed rear wheel bearings, I don't have a press to fool with them so I dropped it at the local mechanic shop told them to replace them and give it some trans fluid if it needed it. They did, and it did need a little fluid. I've been driving it around as often as I can trying to work out the 1/4 tank of stale gas mixed with the fresh I put in and the trans is still hesitating and the starts stayed hard. When you can start, it there are no misses it runs like a charm.

Issues:
1. Cold or warm it is hard to start. Less so when cold taking 2-6 turns at the key and 6 or a fail to start after warm.
2. Code P1770 which is a Diff lock solenoid malfunction. Probably a loose or bad wire. This is a lower priority issue right now as its an automagic trans and wont be anywhere I'll be spinning one tire for a few months.
3. Odd transmission behavior. Hesitating or going up and down a gear rapidly when applying gas, usually stops after being driven.

Where I'm at:
First things first I bought the FSM from Ebay because I have the hots for this Rav and for the low price of 40ish bucks I'd like to have it as a reference. Pulled the code off the scanner for the diff. Then I checked and yanked what I can only assume are 10+ year-old crab-claw denso plugs replaced them with the NGK iridium equivalent and replaced the factory fuel filter. Swapped the old battery for a new battery. I tried starting it, still hard starting warm or cold. I found this forum and found several posts in 4.1 with similar issues. I checked the ECT via the scanner, it reads about ambient temp and when the car runs for a while it reads in a range I would assume my coolant would be at. MAP sensor is reading correct pressure for this elevation according to a google search and it varies correctly when I step on the throttle. I can clearly hear the fuel pump sending fuel when I turn the key to on. I got stranded at an autoparts store and on a whim I tried hitting it with starter fluid and the thing started second try warm. Can I safely say this is a strictly fuel supply related issue? Could it still be a cam or crank sensor issue? Is there anything I'm missing? I'm not skittish about going in and replacing either one myself but I would like to save them for last in the things I try.

I've read about VSV and EGR going out on 1st gen Ravs would they cause a hard start like this maybe be related to the odd transmission behavior but I don't see the rpms going up or down I only feel it
 

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The forum has had a fair number of reports of a failed ECT sensor. I would first check your sensor's resistance:


 

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Thanks, I'll admit I was lazy and relied on the scanner's live feed to see the temps and any fluctuations. as soon as the sun comes up ill ohm out that sensor and post the results.
 

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The OP's post is a little too long for me to read well this early, bleary-eyed morning ... :)

A few thoughts: new air filter, loosen the gas cap (giant sucking sound, then runs?), possible fuel pump (so test the pressure), replace the spark plug wires and coils, replace the ground strap and add a custom one directly from the negative terminal to the block (search on here).

They'll also not start/run (well) if the timing belt has jumped.
 

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Elle_rav4
Checked the resistance on the ECT, reads 6.09 Kohms at 32 dungarees Frankenstein seems smack dab in the middle for the chart and agrees with the readings I pulled from my scanner's live feed. I didn't bother checking the WTS because its so cramped in there and its not giving me any guff.

Lugnut,
I figured everybody wouldn't want to read the whole story so I separated it into the background, issues, and where I'm at. Figured it would be easier for people to TLDR straight to issues and where I'm at
.
Air filter is clean as a whistle.
Gas cap sounds like it is letting out pressure, not sucking in but I'll have to wait until tonight to put my ear right next to it and know for sure. I listened to it when i changed the filter but that was a day or 2 ago.
Wires and coils are on the menu for the very near future. Could I test the ground strap idea by just putting some copper around one of the hooks on the block and connecting that to the neg?
 

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iirc when I was looking at the scanner it was adding 5 or .5 or -5 degrees of timing when at low rpms but I'd have to check tonight or rent one of those flashers Sunday. I don't remember clearly because I was more concerned with the ECT readings. and o2 voltage
 

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You ought to check the ECT sensor after warm-up as well. After all, this is when the no start/hard start condition occurs. I would just want to eliminate it as the cause, since the sensor is so easy to unplug and check the resistance.
 

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I decided to give that ECT a check after warming up the car and I wanted to check the grounds on the engine. So I got the Rav fired up in 2 tries, take it for a short drive and pulled the ECT plug while it was running. I got my reading and it's in spec.

I shut the engine off and checked the grounds, 12v on every point I checked. I didn't check them all because I haven't been having the usual grounding issues like random things turning on or off. I go to fight the warm car to start so I can check the ground while it's running and it fires up first try, not a bit of argument. It surprised me because it was a warm day compared to the last few I've had to work on the rav. To check for a possible miracle or blessing from the troubleshooting fairy I shut it off and I get it started in 2 tries, kill it again and it wont start for any amount of love or money maybe 20 tries without a hint of starting. I noticed that the fuel pump was only turning on and pressurizing every two or 3 turns. I'm thinking bingo that's an intermittent event maybe a relay is bad or something. So I lifted the backseat and tried to get the plug off the pump and it wouldnt budge and I didnt want to risk damaging it by yanking or prodding too much when I know theres a video out there somewhere I can watch to do it the right way. I started thinking while I checked the google machine for a video, what if the pump is fine? It sure works fine when the engine is running, and I'm not starved of fuel when I goose it on the highway. Other than initial startup this pump functions as it should. When I had used starting fluid days ago when it didn't want to start it fired up and got fuel immedietly. I'm leaning towards my air to fuel ratio being way off after it gets warm or something I'm missing completely.

Out of frustration I hooked my battery charger up and set it onthe engine start setting, hooked my scanner up and gave it the business. I wanted to force it to throw a code. And after athe better part of an hour trying to start it it started hit 1000rpms and dropped to 600ish rpms and ran like hell sputtering and shaking for about a minute till it died. I pulledthe code and I had my diff solenoid code and a code for the camshaft position sensor. I ordered one and took some notes off Elle_rav4's post about setting the air gap correctly.

I'm still going to check the pump my next day off but for now I got a few days of 12hr shifts ahead of me.
147123
 

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Discussion Starter #9
I think this sensor would my explain my jerky acceleration that I've been blaming on the transmission too.
 

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You say the P1770 is an easy fix so I would start there, it could be the cause of your transmission problem.
The fuel-pump does not turn on with the key, it is controlled by the ECU. People have spent a lot of time, chasing that dragon.
When the battery is unplugged the ECU also forgets some settings that made the engine run good. It often takes some city style driving patterns before the ECU relearns everything that was forgotten.
 

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Just because you move the key to on, doesn't mean you want to start the engine, so why start a pump you may not need?

From the factory service manual:
Fuel Pump Control Circuit
CIRCUIT DESCRIPTION:
In the diagram below, when the engine is cranked, current flows from terminal ST of the ignition switch to the starter relay coil and also current flows to terminal STA of the ECM (STA signal). When the STA signal and NE signal are input to the ECM, Tr is turned ON, current flows to coil of the circuit opening relay, the relay switches on, power is supplied to the fuel pump and the fuel pump operates. While the NE signal is generated (engine running), the ECM keeps Tr ON (circuit opening relay ON) and the fuel pump also keeps operating.
 

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Oh ok then thanks a ton.

I'll do some research on that diff solenoid and consult my FSM. The new crank sensor should be here tomorrow but I'll likely be swapping it out friday and I'll definately keep the thread updated on my troubleshooting process if this repair doesnt fix the warm hard start issue. My next targets will likely be the vsv and egr I read that they can be linked to hard starting by throwing off your air to fuel ratio. I'm inferring that the starter fluid getting the warm engine to start means I have a lack of fuel hindering my engine. That's also why I was looking so hard at the fuel pump before your comment.
 

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-- Above you seem to interchange camshaft position sensor and crankshaft position sensor. Your Rav4 has one of each. Which one are you replacing? The crankshaft position sensor is hard to get to, but you can do a resistance check of it without too much difficulty.

-- Any idea how old the plugs and wires are? I would evaluate and possibly replace these first thing, as they can be thee problem here.

-- When the no-start happens, I would be checking for spark.

-- I concur with your checking the cam and crank sensors and also Lugnut's and Roundabout's suggestions.

-- I doubt it is the EGR system. I would leave the EGR system alone until further notice.
 

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Sorry that was mistake I meant camshaft sensor. I think it would be prudent of me to check the resistance of the crank sensor too. Consider it on my to do list.

Plugs are brand new. I just installed them. Wires are <2-3yrs they still have that non dried out look to them. Coils look recent too. I'll still be replacing them.

I was gonna try and rent a sparkchecker or just buy one if I find myself by harbor freight. I had kinda leaned away from spark being the issue when I got the warm engine to start with starter fluid. Am I wrong to rely on that this heavily? That just kinda screamed a lack of fuel to me.

I'm gonna replace the cam sensor. I'm not a big fan of yanking off parts and throwing new parts on all willynilly. I think I have pretty good reason to swap it out because it's two decades old and a fairly common root of issues with hard starting. I have one arriving tomorrow. I'll check the new one with my meter and compare it to the one I pull out. Any idea on what the resistance should be? I can check my FSM but if someone had a chart handy that would save me flipping through the index on both books.

As far as checking a crank sensor I read that it's difficult to get to and the prospect of getting to it, checking, and then possibly having to replace it is something I'm not eager to try. I have large hands and timing belts make me nervous to work around. I'm an amateur car mechanic at best, I troubleshoot machines and processes at work and I try to do all my own maintenance on my vehicles but I'm just here to learn and enjoy taking some neglected piece of machinery and making it into something cool that I can be proud of.

I had a blast fixing my motorcycle it was my first real dive into infernal combustion engines. Cars are much more large and complicated. I think I'm going to have a good time with my rav this winter. Thanks for the help and suggestions.
 

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I forgot about the starter fluid. I agree with your reasoning regarding the starting fluid and sparks. Still, I am wondering if a weak spark is present, and the starter fluid was helping ignition.

Camshaft position sensor resistance specs:
835 to 1400 ohms when cold
1060 to 1645 ohms when not

Crankshaft position sensor resistance specs:
985-1600 ohms when cold
1265-1890 ohms when hot

Ignition coil secondary, resistance specs:
9.7-16.7k ohms when cold
12.4-19.6k ohms when hot

Clues on checking the crankshaft position sensor resistance:
--
. Follow the wiring shown in the video up towards the alternator, more or less. You should come to a connector. Disconnect the connector and take resistance readings.

-- Member "Demoder" points out the crankshaft position sensor at 23:38 of the DIY timing belt video at
.
 

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Hey thanks for that data! That will help me out a ton. Weak spark is definitely in the realm of what could be giving me guff. I had seen another video from Demoder when I was putting on my steering wheel straight and resetting the clockspring. She does her own leather wrapping around the steering wheel and I wanted to try it. That video is exactly what I need if I end up having to replace that crank sensor. It's long, detailed and explained well enough for me to understand. It's also got some other stuff I might as well do while I'm in there.
 

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Update.

Weather did not allow for the full Friday of working on the Rav. I did manage to get the camshaft position sensor replaced. Sadly it took me all of the time I had to replace. I have large hands and I don't have any 90lb double-jointed Filipino friends to help me replace the sensor. When I got it out and checked, the resistance was in the 1200 range and it was in the 40s outside so that within spec but on the high end. I think the real problem was the 20yrs of iron filings and oil attached to the sensor. I could have probably got away with cleaning it and reinstalling it.
147240


So far, the car starts better, cold and warm there is a definite improvement. It feels like its starting more like it should. I had hopes that this would clear up what I called the odd transmission behavior but its still present. I'm gonna do the coils and wires today or tomorrow and call this fixed if it goes a month without hard starting to the degree it originally was.
 

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I trust you have envisioned that the crankshaft position sensor has just as much oil and filings on it. This seems to be the usual case from my experience and others'.

At some point before you go "innawoods," maybe you can do a full timing belt job (replacing the timing belt, the usual related parts, and possibly the crankshaft position sensor)? Put demoder's excellent video on a large monitor, have a buddy and a second vehicle handy, put refreshments on the workbench, and do it (maybe over a couple of days, as it is the first time)?
 

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I still think the P1770 could be causing the transmission feeling you describe.
If the hydrolics are trying to shift power between the axles, it will rob a little power from the engine.
 
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